Fighting resumes in Southern Sudan

An army spokesman said the former rebel SPLA had attacked with tanks and that both sides had suffered heavy losses.

UN officials say the clashes started a day after they began supplying aid to some 50,000 people who fled the town after last week's clashes.

The long-running dispute over the status of Abyei threatens a 2005 peace deal which ended years of war.

An administration has yet to be set up in Abyei, which is claimed by both the north and south.

The market area in Abyei was destroyed by mortar fire in last week's fighting and most of the town's population left.

There are 300-400 UN peacekeepers in Abyei, who are monitoring the situation, Orla Clinton, a spokeswoman for the UN's Office for the Coordination of Humanitarian Affairs told the BBC's Focus on Africa programme.

She said aid was being distributed in the nearby town of Agok.

"The people who are fleeing are very concerned, they are scared," she said.

Brigadier General Osman al-Aghbash told the state-run Sudan News Agency that SPLA forces attacked an army camp with tanks and heavy weapons "with the intention of taking over the town".

The 20-year north-south civil war, separate from the Darfur conflict, was said to have cost 1.5 million lives.

Under the 2005 peace deal, the SPLA joined a government of national unity.