Didiri Mohamed Ahmed, the northern official in charge of Abyei, said a meeting of officers and politicians had agreed to end a build-up of troops around the central Sudanese town and laid out a plan to replace them with new joint north-south military units.

But a prominent member of the southern Sudan People's Liberation Movement (SPLM) played down the progress, saying huge political differences still remained over the demarcation of Abyei and its nearby oil fields.

Tens of thousand of civilians fled Abyei last week during clashes between northern and southern troops, prompting fears of further conflict.

Northern and southern leaders have blamed each other for starting the fighting that left more than 20 northern soldiers and an unknown number of southerners dead.

SPLM secretary general Pagan Amum said on Monday Sudan was on the brink of a fresh civil war following the clashes.

Both the north and the south covet Abyei, which is close to oilfields that produce up to a half of Sudan's daily 500,000-barrel output, and have remained at loggerheads over its boundary and administration.

The borders of the region were left undecided in a 2005 peace deal that ended two decades of civil war and created a coalition north-south government.

Didiri Mohamed Ahmed said senior military leaders and officials from both sides met on Tuesday for a session of the country's Ceasefire Political Commission, observed by the United Nations.

"The two parties committed themselves to de-escalation," he told Reuters. "They reiterated that there is no intention to renew hostilities. There is no return to war."

FRESH FORCE

A national police force would eventually be set up inside the battle-scarred town, alongside a fresh force of joint north-south soldiers, while an investigation would look into the causes of the recent clashes, Didiri said.

Northern Sudan Armed Forces troops would maintain their current position in the town, with the southern Sudan People's Liberation Army stationed south of the town, until a new administration for Abyei could be agreed, allowing the troops to withdraw, he added.

There was no one immediately available from the United Nations or the SPLM officers present at the committee to confirm the conclusions of the meeting.

Yasir Arman, deputy secretary general of the SPLM, dismissed the outcome of the meeting.

"This was a technical committee and we are not going to get a solution to the Abyei problem through a technical committee," he told Reuters. "The only solution is a political one."

Arman said senior political leaders from both sides had met in Khartoum on Tuesday without reaching an agreement and were planning to meet again on Wednesday.

Earlier on Tuesday, the SPLM pulled out of talks between Sudan and a U.S. envoy, saying the negotiations could have emboldened northern soldiers to attack Abyei.

Arman said the SPLM had withdrawn because it thought northern Sudanese politicians may have become emboldened by the prospect of a return to normal relations with the United States, which has imposed sanctions on Sudan since 1997.

"We think maybe the dialogue between Khartoum and Washington encouraged them to attack Abyei," he said.