Sudanese warplanes bombed a UN peacekeepers' base, damaging it but causing no casualties in the first such attack since a recent escalation of fighting with South Sudan, officials said Monday.

Bombing raids on Sunday also killed nine civilians elsewhere in South Sudan's Unity border state, said the area's information minister, Gideon Gatpan.

"They launched another bombardment here yesterday," Gatpan said, adding that bombs were dropped near the oil-producing state's capital Bentiu, as well as in the village of Mayom, some 60 kilometres (40 miles) to the west.

"In Mayom... it killed seven civilians and wounded 14, two bombs fell inside the UN camp in Mayom and destroyed a generator and a radio," Gatpan said.

"Two fighter jets released eight bombs east of Bentiu," he added. "Others fell in villages around Bentiu, where two people were killed, including a pregnant woman, and eight people were wounded."

UN peacekeeping mission spokesman Kouider Zerrouk confirmed the attack on the small base, but said "there were no casualties, no one was wounded".

Fighting broke out between the rival armies of Khartoum and Juba last month, but escalated last week as Southern troops seized the contested Heglig oil field and Sudan launched counter-attacks and waves of air strikes across the border.

The hostilities are the worst since South Sudan's independence from Sudan in July, and world powers have condemned the fighting, as fears grow of a wider escalation of the conflict.

The most intense fighting has been centred on Heglig, which contributed about half of Sudan's total oil production.

But South Sudan's army accused Khartoum on Sunday of trying to open a second front in the northeast of its territory, an area so far spared the fierce border clashes of recent days.

The South said its forces had repulsed fresh attacks launched by Khartoum's army early Sunday near the border village of Kuek in Upper Nile state, a widening of the fighting outside Heglig.

Talks are stalled between the foes, but Egyptian Foreign Minister Mohammed Kamel Amr arrived in Juba after talks Sunday in Khartoum, where he met Sudan's President Omar al-Bashir.

"We have come to explore ideas and ways to try to reach a peaceful resolution between the two nations," Amr told reporters. "We don't have a specific proposal yet.

Khartoum's official SUNA news agency said Sunday that Bashir welcomed Egypt's role, but he told Amr that Sudan refuses to negotiate with the South unless it withdraws from Heglig.

South Sudan has said it will not withdraw unless Khartoum pulls out of the neighbouring contested Abyei region, which Sudanese troops seized last May, forcing some 110,00 people to flee southward.

Southern Information Minister Barnaba Marial Benjamin welcomed Amr to Juba, saying the role of Sudan's former colonial ruler was "crucial".

Last July, South Sudan separated after an overwhelming "yes" vote under a peace deal that ended Sudan's 1983-2005 civil war.

The African Union has for months been mediating unresolved issues over oil, border demarcation and citizenship between the two states.

The latest fighting prompted Khartoum to pull out of those talks, and analysts said any type of negotiations in the current climate were unlikely.

Some two million people died in Sudan's civil war, one of Africa's longest, before the peace deal that opened the way to South Sudan's independence.

When the South separated, Khartoum lost about 75 percent of its oil production and billions of dollars in revenue, leaving the Heglig area as its main oil centre.