Hundreds of thousands have been displaced by the violence
His five-day visit comes amid signs the government may allow a UN peacekeeping force into the war-torn area.
On Friday Khartoum and the largest rebel group in Darfur signed a peace deal. Two smaller rebel groups rejected the agreement, after talks in Nigeria.
The three-year conflict has killed about 200,000 people and left about two million homeless.
'New willingness'
UN Emergency Relief Co-ordinator Mr Egeland is due to go to Darfur on Sunday, in the first visit by a UN official to the region since the peace deal was signed.
He is expected to visit southern Darfur, where fighting has broken out recently.
Mr Egeland will have talks with local leaders and visit refugee camps before heading to Khartoum on Monday for meetings with Sudanese officials, according to French news agency AFP.
He said prior to his visit that access for aid workers in Darfur was at its worst level in two years.
The trip came amid hopes Khartoum might accept a UN force to take over from African Union (AU) troops in Darfur.
Khartoum has said in the past it would only consider inviting in UN troops if a peace deal was reached.
But on Saturday the US welcomed Khartoum's "new willingness".
Citing comments by government representatives indicating they were now willing to accept the UN force, US Ambassador to the UN John Bolton said they viewed "this as... the first positive outcome from the Abuja peace agreement", according to the AFP news agency.
Earlier UN Secretary General Kofi Annan urged Khartoum to issue visas to his team of assessors so they could begin planning for the arrival of an international peacekeeping force to replace the 7,000 African troops later in the year.
Peace deal
The peace plan, brokered by the African Union, creates a temporary regional government for Darfur, in which rebels will take part.
DARFUR DRAFT PEACE PLAN Pro-government Janjaweed militia to be disarmed Rebel fighters to be incorporated into army One-off transfer of $300m to Darfur $200m a year for the region thereafter Compensation for those forced to flee their homes Regional government, if approved in a vote
Life 'worse' for civilians Q&A;: Darfur crisis Have Your Say: Darfur crisis
The pro-government Janjaweed militia are to be disbanded and the rebels incorporated into the security forces.
Deadlines came and went in recent days, as diplomats exerted pressure on parties after all the rebels had rejected the original draft.
In the end the Khartoum government and the Sudanese Liberation Movement (SLM) said they were willing to sign, despite reservations on both sides over power sharing and security.
But the smaller faction of the SLM would not budge, blaming a lack of trust in the security arrangements.
The smallest rebel group, the Justice and Equality Movement (Jem), called for fundamental changes to the document.
Its chief negotiator reiterated the rebels' demands for the post of vice-president in the Khartoum government and for Darfur to have a greater share of national wealth.
'Genocide'
Aid organisations say the conflict has created one of the worst humanitarian crises in the world.
The rebels took up arms in 2003, accusing the government of discriminating against the black African residents of Darfur.
Pro-government Arab militia then launched a campaign, described as "genocide" by the US.
The Sudan government denies backing the Janjaweed militias accused of mass killing, rape and looting.
The Government of Sudan has expressed that the  Darfur Peace Accord with main rebel group, Sudan Liberation Army, led by Minni Menawi, can overturn the previous rejection of UN Peacekeepers. So far, only African Union Peacekeepers were allowed in Darfur.

"The Sudan government will be open for any assistance," Bakri Mulah, secretary-general for external affairs in Sudan's Information Ministry, said in Khartoum, Sudan.

In New York, John R. Bolton, the US ambassador, on Saturday welcomed Khartoum's new willingness to accept a UN peacekeeping force to take over from AU soldiers in the Darfur region. He cited the Sudanese government representatives' comments  to indicate they were now willing to accept the UN force. He said, " We view this as a very encouraging sign, the first positive outcome from the Abuja peace agreement. "

In the meantime, top UN humanitarian official Jan Egeland has arrived in Sudan to review the situation in the Darfur region. He is expected to visit southern Darfur, where fighting has broken out recently.  It is the first visit by a UN official to the region since the peace deal was signed.

He said that access for aid workers in Darfur was at its worst level in two years. "At the moment Darfur is slowly being strangled, it's dying in front of us, half of the population now has become war victims...so I believe, yes, we are turning the corner, but the whole world has to put pressure on the parties." said Mr Egeland, the UN's Emergency Relief Co-ordinator.  

Earlier, UN Secretary General Kofi Annan requested Khartoum to issue visas to his team of assessors so they could plan for the deployment of an international peacekeeping force to replace the 7,000 African Union troops later in the year. The AU troops, now running out of funds, had largely been ineffective in stopping atrocities, leaving millions to struggle in camps with little food or water. While details for a UN peacekeeping force are finalised, the US diplomat said the US had asked Rwanda to send in some 1,200 troops to supplement the AU forces.

In a recent development, an unknown assailant shot a Spanish United Nations Aid worker in Chad. She is working in the eastern part of Chad to assist the refugees from Darfur region. 2,00,000 refugees have crossed the border to escape from the violence in Darfur. She is in critical condition.