Sudanese war planes on Monday launched a fresh bombing raid on Bentiu, capital of the oil-rich South Sudan border state of Unity, killing at least one child, officials said.

"This is a serious escalation, and a violation of the territory of South Sudan... I think it is a clear provocation," Mac Paul, the South's deputy director of military intelligence said.

Four Togolese peacekeepers have been shot and wounded in separate attacks in Sudan's Darfur region, the AU-U.N. mission said on Saturday.

The attacks occurred on Friday, the same day the head of the African Union-United Nations Mission in Darfur (UNAMID),Ibrahim Gambari, expressed concern that rebels were exploiting a deadly stand-off between Sudan and South Sudan.

Rebels in Sudan's Blue Nile said on Friday that they had killed 79 government troops and militiamen in two ambushes in the ethnically divided state near the border with South Sudan.

The attacks came on Tuesday and Wednesday in roughly the same area, mountainous terrain about 35 kilometers south of the state capital Ed Damazin, said Arnu Ngutulu Lodi, spokesman for the rebel Sudan People's Liberation Movement-North (SPLM-N).

The South Sudan army claimed Saturday to still be in control of Heglig after Khartoum said it had launched an offensive to recapture the disputed oil hub.

"The SPLA is controlling Heglig," spokesman Philip Aguer told AFP. He said that the Southern army had repelled soldiers of the Sudanese Armed Forces in the village of Kelet some 40 kilometers (25 miles) from Heglig on Friday, the fourth day of the worst clashes since South Sudan's independence last year.

Sudanese warplanes launched a second day of bombardment of oil-rich areas of South Sudan, after bloody clashes between ground troops of the rival states, a Southern government official said Tuesday.

"After a day of attacks by air and ground troops on Monday, this morning we heard the Antonov (aircraft) return, and dropped two bombs," said Gideon Gatpan, information minister for South Sudan's Unity state.

Actor George Clooney and several members of the U.S. Congress were handcuffed and arrested Friday outside Sudan's embassy as they demanded an end to an offensive they fear will cause a humanitarian crisis.

Swarmed by flashing cameras and TV crews, Clooney led more than one dozen prominent campaigners to the steps of Sudan's mission in Washington's Embassy Row, ignoring several warnings by police to leave the premises.

Bloody civil war in Sudan's South Kordofan border state risks becoming as brutal as the conflict in its western region of Darfur, a rights group official and former U.N. chief in Sudan said Tuesday.

Government aircraft regularly bomb civilians in the Nuba Mountains of South Kordofan, actions "tantamount to war crimes," said Mukesh Kapila, of the Aegis Trust, a British-based rights group which campaigns against genocide.

South Sudan on Thursday accused the Khartoum government in the north of bombing 74 kilometers deep inside its territory, and of sending troops into contested border areas.

"They have flown into our territory 74 kilometers and are violating South Sudanese airspace," Information Minister Barnaba Marial Benjamin said of the airstrikes midday Wednesday.

United Nations international staff have returned to Sudan's South Kordofan for the first time in months, the U.N. said on Saturday, as global concern mounts over food shortages in the war-torn state.

"Today, FAO and OCHA flew back there by helicopter and they landed safely" in the state capital of Kadugli, Damian Rance, a public information officer at the UN Office for the Coordination of Humanitarian Affairs (OCHA), told AFP.

None of the 29 Chinese workers abducted after an attack in a volatile region of Sudan have been freed, Chinese state media said Tuesday, dismissing reports that some of the workers had been released.

The workers were abducted Saturday by militants in a remote region in the country's south. Sudanese state media reported Monday that 14 of them had been freed, but the official Xinhua News Agency and China Daily newspaper said all 29 were still being held.