The men are planning to attack Mumbai over the Christmas and New Year period and police have released a sketch of one of them.
"It is going to be a violent attack which will cause disruptions," said Himanshu Roy, joint commissioner of Mumbai Police. "They have recently arrived in Mumbai. We are not in a position to reveal their nationalities now but they are LeT members."
The four men were named as Abdul Karim Musa, Noor Abul Elahi, Walid Jinnah and Mehfooz Alam.
A US counterterrorism official, speaking on condition of anonymity, acknowledged the possibility LeT might attempt to strike over the holidays.
"There's no question LeT remains interested in pulling off another large-scale attack in India, and we are alert to the possibility that LeT might again try a holiday attack," the official said, speaking on condition of anonymity.
LeT is widely believed to have been behind the 2008 terror attacks on Mumbai that killed 166 people. A second attack on Mumbai could damage India's economy and an attack originating from Pakistan could force a swift Indian response, which would destabilise regional security.
A US diplomatic cable released by WikiLeaks earlier this month and written in September 2009 claimed that the Pakistan government continues to support four militant groups, including the Taliban's Haqqani network and LeT, and could not be persuaded to abandon them.
On November 26, 2008, 10 heavily armed gunmen stormed downtown Mumbai, opening fire in the city's main train station and a bar popular with tourists. They sieged two luxury hotels and a Jewish centre for three days, killing 166 people and injuring hundreds. The lone surviving gunman, Mohammed Ajmal Amir Kasab, was sentenced to death in May.
Tensions have remained high in Mumbai since the attacks, with increased security at the city's hotels, train stations, sea port and airports.
A police official in Mumbai has warned four suspected militants of Pakistani origin have entered the city, the capital of Maharashtra, India, and claims they are plotting attacks in the city. Police are now searching for the four people, thought to be members of Lashkar-e-Taiba (LeT), the Islamic  militant group the Indian government holds responsible for the coordinated attacks which hit Mumbai in 2008. Joint police commissioner Himanshu Roy says intelligence suggests "the threat is serious."
Lashkar-e-Taiba are thought to be responsible for the coordinated attacks which hit Mumbai in 2008. 

A United States counter-terrorism official said the attacks are likely imminent, and will occur over the Christmas and New Year period. "There's no question LeT remains interested in pulling off another large-scale attack in India," the official said, speaking on condition of anonymity, "and we are alert to the possibility that LeT might again try a holiday attack."

Speaking at a press conference, Roy said "they have recently arrived in Mumbai. We are not in a position to reveal their nationalities now but they are LeT members."


Armed police have been posted around high-profile destinations in the city, and roads around the —seiged by militants in the 2008 attacks—have been closed. Police have released a sketch of one of the militants believed to be in the city.

"The police are on high alert all over the city. We cannot take any of these intelligence inputs lightly in the holiday season," another Mumbai official said. "Since yesterday, we are checking all the possible hideouts, small lodges and guesthouses, railway stations. We are checking all the vehicles that are coming into the city."

166 people died and hundreds more were injured in the 2008 attacks, in which multiple gunmen attacked the  railway station, a hospital, a police station, and numerous hotels, amongst other sites. The attacks were dubbed "India's 9/11" by local media. Only one militant survived the attacks, Ajmal Amir Kasab; in May this year he was sentenced to death by hanging, on 86 charges, including murder, terrorism, and waging war against India.