Peacekeepers on Sunday said Sudan's government had asked them to withdraw from a rebel-held Darfur town, amid reports state troops were preparing to attack the settlement.

The joint United Nations/African Union UNAMID peacekeeping force said it was trying to convince Sudan to let its troops stay in their base in the south Darfur town of Muhajiriya so they could continue to protect more than 30,000 civilians in the battle-scarred area.

Muhajiriya has been the scene of more than two weeks of fierce fighting between Sudan government forces, troops from the rebel Justice and Equality Movement (JEM) and other fighters.

Fighting in Darfur has escalated in the build up to an expected decision from the International Criminal Court on whether to issue an arrest warrant against Sudan's president on charges of orchestrating genocide in Darfur.

JEM, which holds Muhajiriya, told Reuters its commanders had reported four columns of Sudanese army troops, including one unit with tanks, were approaching the south Darfur town from different directions on Sunday afternoon.

"We think they are planning a large attack," said JEM official Al-Tahir al-Feki. "Our main concern is for the civilians because they will bear the brunt of any fighting. ... They (the government forces) are bringing tanks so they must be preparing to pound the town."

Al-Feki said he had reports government troops from Nyala and El Fasher, the capitals of south and north Darfur, were being supported by militias and other fighters loyal to Minni Arcua Minnawi, the only Darfur rebel leader to sign a peace agreement with Khartoum in 2006. JEM seized Muhajiriya from Minnawi's forces mid-January.

FEARS FOR CIVILIANS

It was impossible to verify the report of the approaching troops independently and Sudan's armed forces could not be reached for comment.

UNAMID spokeswoman Josephine Guerrero said the Sudanese government on Sunday afternoon asked a 196-strong contingent of UNAMID peacekeepers to withdraw from the town, but had not given a reason for the request.

She said the U.N. and African Union's joint special representative in Darfur, Rodolphe Adada, had flown back to Sudan from a conference in Ethiopia to try and persuade Sudan's government to change its mind.

"We are asking that so we can continue what we are doing which is protecting civilians," she said. The peacekeepers were still in the town early Sunday evening, she added.

British campaign group The Aegis Trust said it feared for the safety of Muhajiriya's civilians if UNAMID left. "If UNAMID pulls out of the town, there will be no remaining international observers," said Aegis chief executive James Smith.

When the fighting started last month, aid workers were evacuated and civilians took shelter around the UNAMID base. JEM said civilians were killed and seriously injured, although there have been no verified figures.

Analysts said the fighting around Muhajiriya has been the worst violence the region has seen in a year.

UNAMID, which is supposed to cover a remote region about the size of Spain, has found itself caught up in an increasingly chaotic conflict involving bandits, government forces, insurgent factions, rival tribes and militias.

International experts say 200,000 have died in Darfur since mostly non-Arab rebels took up arms against the government, accusing it of neglect. Khartoum mobilised mostly Arab militias to crush the revolt.

Sudan's government puts the death count at 10,000 and denies activists' accusations that genocide took place during the counter-insurgency.