Top negotiators for Sudan and South Sudan pressed ahead Wednesday with their first talks since deadly border fighting last month took them to the brink of war.

Teams from both sides are in the Ethiopian capital taking part in African Union-led talks which were stalled last month by fierce clashes in border areas, the worst fighting since the South won independence last July.

South Sudan on Wednesday offered a cautious welcome to foe Sudan's pullout of troops from the contested border region of Abyei, a year after Khartoum's army stormed the area, forcing thousands to flee.

"We welcome of course the move by the Republic of Sudan... it's a sign of peace," said Information Minister Barnaba Marial Benjamin.

However, he was still hesitant of Khartoum's motives and whether the pullout was total, despite confirmation by the United Nations of the withdrawal.

"If they have taken this decision, we will see... we are always aware Sudan's government says something else and does something else," he added.

The UN said Sudanese troops had pulled out from Abyei on Tuesday, as the two parties restarted their talks in the Ethiopian capital.

South Sudan had already pulled its security forces out of Abyei in line with a UN Security Council demand for both sides to demilitarise the territory.

Abyei is one of the key disputes between Sudan and South Sudan, which have been fighting each other along their undemarcated border.

Sudanese troops seized the region in May 2011, forcing some 110,000 people to flee southwards, where most remain in impoverished camps.

Abyei was one of a series of issues -- including their common border, oil transit fees and citizenship -- that were left undecided when the two split in July.

Khartoum has said it will only address issues such as contested areas and citizenship once the all-important security concerns have been addressed.

Nothing had filtered out on progress of the talks by early evening Wednesday.

Sudan and its southern region fought a war that left more than two million people dead from 1983 until 2005, when South Sudan was given autonomy under a deal that paved the way for independence.