WASHINGTON — When Saudi Arabia's crown prince visits the White House next week, he's expected to be welcomed as a reformer who's expanded women's rights in one of the most restrictive countries in the world, allowing them to drive and attend sports events.

Yet there is one Saudi woman whom U.S. officials say has not benefited from the prince's rise: his own mother. Fourteen current and former senior U.S. officials told NBC News that intelligence shows Prince Mohammed bin Salman — often referred to by his initials MBS — blocked his mother from seeing his father, King Salman, more than two years ago and has kept her away from him as the young prince rapidly amassed power.

Prince Mohammed, a key ally of the Trump White House, has concocted various explanations of his mother's whereabouts over the years, such as that she's out of the country receiving medical treatment, so King Salman would not know his son has been behind her continued absence, the current and former officials said.

U.S. officials interviewed for this story believe, based on several years of intelligence, that MBS took action against his mother because he was concerned that she opposed his plans for a power grab that could divide the royal family and might use her influence with the king to prevent it. The officials said MBS placed his mother under house arrest at least for some time at a palace in Saudi Arabia, without the king's knowledge.

Last June, at just age 31, Prince Mohammed abruptly displaced his cousin to become crown prince of the oil-rich kingdom. He implemented some economic and social changes in the following months, but also made some brazen power moves at home and in the region. In November MBS oversaw the arrests of more than 200 Saudi officials and businessmen, including prominent princes and rival members of the royal family, in what the government has described as a crackdown on corruption.

President Donald Trump defended the Saudi government for "harshly treating" those who were imprisoned as part of the effort. Trump, and his son-in-law and senior White House adviser, Jared Kushner, have embraced MBS as a close partner and critical player in the administration's Middle East strategy.

The White House announced Monday that the president will meet with the crown prince on March 20, saying Trump "looks forward to discussing ways to strengthen ties between the United States and Saudi Arabia and to advance our common security and economic priorities."

But the meeting, which is part of MBS's multistate tour across the U.S., comes as some senior U.S. officials are increasingly concerned his aggressive tactics could sow more instability in the Middle East.

The U.S. intelligence assessment of Prince Mohammed's actions against his mother, which American officials said has long been concealed from both King Salman and the public, is an example of MBS's willingness to remove any perceived impediment to solidifying his position as Saudi Arabia's next king, the current and former officials said.

Officials said the assessment of the dynamic between MBS and his mother, which has not been previously reported, is based on a combination of human intelligence, intercepts and information shared with the U.S. from other countries.

The determination that the crown prince's mother, Princess Fahda bint Falah Al Hathleen, was being kept from King Salman without his knowledge was first made during the Obama administration, the officials said. That assessment has not changed since Trump took office, according to the current officials.

The Embassy of Saudi Arabia in Washington denied that the princess is under any kind of house arrest or separation from her husband.

Where is King Salman's wife?

The U.S. officials, who spoke on condition of anonymity because of the sensitive nature of the intelligence, said the 82-year-old King Salman has at times been told his third wife is out of the country receiving medical treatment. They said the king has told people around him that he misses her and apparently does not know her true location or status. Multiple U.S. officials have told NBC News previously that their interactions with the king suggest he is not consistently lucid.

At one point during a meeting at the White House in September 2015, King Salman told then-President Barack Obama that his wife was in New York for medical treatment and that he hoped to visit her while in the U.S., officials said. The officials said Obama did not inform the king that his wife was not in New York, but the king's comment was viewed as further evidence of what U.S. officials already had gleaned from intelligence on the royal family.

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In early 2016, U.S. officials picked up communications in which MBS was talking about his efforts to keep his mother from his father without the king knowing, according to current and former officials.

A spokesperson for Obama declined to comment, citing the privacy of the former president's conversations with foreign leaders.

The CIA declined comment on any intelligence on the Saudi royal family. A spokesperson for the Office of the Director of National Intelligence also declined comment for this story.

While Prince Mohammed's power base began expanding at home several years ago, his brashest moves have coincided with the strong and early support he's received from the Trump White House.

Less than two months after his inauguration, Trump hosted MBS at the White House, not the then-crown prince, Mohammed bin Nayef. MBS, who began trying to forge close ties with the Trump team immediately after the 2016 election, has spent hours with Kushner in Washington and Riyadh.

A spokesperson for Kushner, who oversees the administration's efforts to reach an Israeli-Palestinian peace deal, declined to comment for this story and referred questions to the National Security Council, which also declined comment.

'We've all pinned our hopes on him'

Trump officials view MBS as the best hope for seeing economic and social changes in the tightly controlled kingdom.

"We've all pinned our hopes on him," one senior White House official said.

It's a stark contrast to the U.S.-Saudi relationship during Obama's presidency. Then the two countries clashed over Obama's diplomatic outreach to Iran, Saudi Arabia's main regional adversary.

Now Saudi Arabia is integral to U.S. policy goals in the Middle East, particularly when it comes to blunting Iran's influence in the region and reaching an Israeli-Palestinian peace deal.

President Donald Trump and Saudi Crown Prince Mohammed bin Salman in the State Dining Room before lunch at the White House. Nicholas Kamm / AFP - Getty Images file

In May, Trump made Saudi Arabia the first foreign country he visited as president. A month later MBS unexpectedly supplanted Prince Mohammed bin Nayef as crown prince. As part of the power shift, bin Nayef was put under house arrest, though the restriction was later lifted.

The crown prince's younger brother, Prince Khaled bin Salman, was named Saudi Arabia's new ambassador to the U.S. in July. Both have the same mother.

"The president and Jared very much see Mohammed Bin Salman as their man in the region," said Andrew Bowen, a visiting scholar at the American Enterprise Institute who focuses on Saudi Arabia and the Gulf States.

Trump backed a Saudi-led blockade of Qatar over the advice of some of his own advisers and supported the government's jailing of hundreds of wealthy Saudis accused of corruption. "I have great confidence in King Salman and the Crown Prince of Saudi Arabia, they know exactly what they are doing," Trump wrote on Twitter in November as the arrests came under international scrutiny. "Some of those they are harshly treating have been 'milking' their country for years!"

Many prisoners were released in recent weeks after agreeing to undisclosed financial settlements with the government.

An interview offer, with strings attached

Bowen cautioned, however, that Trump's strong support for MBS's early moves could backfire over time due to the young prince's own "insularity and his own recklessness."

One person close to the royal family said Prince Mohammed and his mother had a falling out several years ago in part because he was concerned she was trying to empower her siblings. This person said MBS wanted to avoid a dynamic that played out with a previous Saudi king in which the brothers of one of his wives became extremely powerful and wealthy.

Fatimah Baeshen, a spokesperson for Saudi Arabia's embassy in Washington, vehemently denied that the crown prince has kept his mother away from the king without the king's knowledge.

"It is absolutely not true and if you would like to ask Her Royal Highness the Princess yourself, this includes asking her in-person, we would be happy to arrange it immediately," Baeshen said in a statement.

NBC News, which first contacted Baeshen about this story on Dec. 22, 2017, did not accept the offer to speak with the princess because the Saudi government would not allow NBC to disclose that one of its reporters had met with her or use any information she provided for this story under any conditions, including if she was granted anonymity to talk about sensitive matters as others in this story were.

Another spokesman for the Saudi embassy then offered for NBC News to speak with sources close to the crown prince's mother, an offer NBC News accepted.

On Jan. 30, Kabil wrote in an email that it was the Saudi government's impression that NBC News would speak with the crown prince's mother and she "would then put you in touch with her circle of confidantes."

NBC responded by reiterating its position that a reporter would not meet with the crown prince's mother unless NBC could disclose that a meeting took place. NBC asked again for names of people close to her whom reporters could contact independently.

Kabil responded by calling NBC's position "reckless," and said it would cause the princess distress and force her into the public spotlight.

"The story is absolutely false and highly offensive," Kabil wrote. "The Princess offered to meet with you privately to personally refute the story but you declined. Instead, you have chosen to rely entirely on unnamed and anonymous sources for your reporting. Thus, your viewers cannot judge your sources' motives or credibility."

I have great confidence in King Salman and the Crown Prince of Saudi Arabia, they know exactly what they are doing.... — Donald J. Trump (@realDonaldTrump) November 6, 2017

Assessing the inner workings of the Saudi royal family can be difficult, particularly when it comes to women, U.S. officials and Saudi experts said. They noted that the wife of a king under house arrest, confined to a palace or denied access to her husband could go unnoticed for quite a while. Such a dynamic could be difficult to determine because the king's wives are rarely seen in public, they said, and it is considered disrespectful to ask about a Saudi man's wife.

Brian Katulis, a senior fellow for national security at the Center for American Progress who has met with top Saudi officials, including the crown prince, said it's been particularly challenging to determine what's happening in the kingdom over the past year because of efforts by different factions to frame what's unfolding.

"In absolute monarchies controlled by a ruling family like Saudi Arabia, it's hard to tell what is actually going on inside these power shifts," Katulis said, adding that he had not heard of any issues related to the crown prince's mother and had no way to verify it.