Secretary-General Kofi Annan is seeking to speak to Sudanese President Omar Hassan Ahmed al-Bashir after his Government banned a visit by the top United Nations relief official to the Darfur region, where fighting between the Government, pro-government militias and rebels has killed scores of thousands and uprooted millions.

Under-Secretary-General for Humanitarian Affairs Jan Egeland's plane was refused permission to land on Sunday at the start of what was to have been a five-day visit to Africa's largest country, where the UN is heavily involved in trying both to ease the Darfur crisis and to promote the rehabilitation of the recently pacified South.

Mr. Egeland eventually flew from Uganda to Juba, capital of southern Sudan, by commercial plane but, after spending a day in the town of Rumbek, he left the country when the Government's refusal to let he him visit Darfur aborted the trip.

"The Secretary-General regrets that the Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, Jan Egeland, was not permitted by the Government of Sudan to visit Darfur," a statement issued by Mr. Annan's spokesman said.

"The pressing and urgent humanitarian requirements of Darfur are a priority for the United Nations and coordination efforts to sustain this large programme were at the centre of Mr. Egeland's visit.

"The Secretary-General will be seeking to speak to President Omar Hassan Ahmed al-Bashir on this matter," the statement added.

For the past three years Mr. Egeland, who is a well-known champion of international humanitarian assistance around the world, has been highlighting the plight of those caught up in the conflict in Darfur in western Sudan, where more than 180,000 people have been killed and 2 million more displaced in the fighting.

An enquiry set up by Mr. Annan found that there had been war crimes and crimes against humanity committed by both sides, but primarily by Government forces and militias. It referred a list of 51 as-yet undisclosed names to the International Criminal Court (ICC) for possible prosecution.