Neither the United Nations nor the African Union can impose its will on Sudan, President Omar al-Bashir said on Thursday, after fresh fighting along the border with South Sudan.

"We will implement what we want and, what we do not want, no one can impose upon us -- neither the U.N. Security Council nor the African Union Peace and Security Council," Bashir said.

The United Nations said bodies lay in the battle-damaged town of Girayda on Wednesday, after a brief occupation by rebel troops in the war-plagued Darfur region of western Sudan.

Sudan's army regained control of Girayda town and the surrounding area but nine government soldiers died in the effort, reported the Sudanese Media Center (SMC), which is close to the security apparatus.

Sudan has stopped fighting inside South Sudan in line with a U.N. resolution, but will continue battling Southern troops who remain on northern territory, the foreign ministry said on Friday.

"We are not now conducting hostilities inside South Sudan but on our territory we will not halt the fighting until South Sudan's troops withdraw," ministry spokesman Al-Obeid Meruh told Agence France Presse shortly before the 1500 GMT U.N. deadline for both sides to cease hostilities.

Sudanese warplanes and long-range artillery bombarded South Sudan border regions Thursday, defying a U.N. Security Council ultimatum to end hostilities or face possible sanctions, the South's army said.

"Their aircraft dropped bombs and artillery was fired targeting an SPLA (Southern army) base...this is an indication of preparation for a ground attack," said Southern army spokesman Philip Aguer.

Sudan and South Sudan's armies were locked in a tense standoff Thursday hours after a U.N. Security Council ultimatum to end hostilities or face possible sanctions.

"We have no reports" of clashes or air strikes Southern army spokesman Philip Aguer said, after the U.N. body on Wednesday demanded the fighting stop within 48 hours.

A surging number of hungry refugees are fleeing fighting between Sudanese troops and ethnic rebels, with some reduced to foraging in the wild, the United Nations said on Monday.

There has been "a notable increase in the number of new arrivals" who have crossed the border from South Kordofan into South Sudan's Unity state, the U.N. humanitarian agency (OCHA) said in its weekly bulletin.

A governor in a Sudanese border state has set a one-week deadline for 12,000 ethnic South Sudanese gathered south of Khartoum to leave the country, state news agency SUNA reported on Sunday.

"The wali (governor) of White Nile state, Yusuf al-Shambali, confirmed that he has set May 5 as the deadline for the Southerners waiting in Kosti," a way station south of the capital, it said.

Four foreigners investigating the debris from recent fighting between Sudan and South Sudan have been captured in the Heglig oilfield area, Khartoum's military said on Saturday.

Sawarmi Khaled Saad, the army spokesman, identified the foreigners as a Briton, a Norwegian, a South African and a South Sudanese.

Sudan on Saturday rejected U.N. Security Council involvement in efforts to end weeks of border clashes with South Sudan, which said it repelled an attack by Khartoum-backed rebels.

"Sudan confirms that it rejects any efforts to disturb the African Union role and take the situation between Sudan and South Sudan to the U.N. Security Council," Foreign Minister Ali Karti said after a month of deadly clashes which have raised fears of a wider war.

The South Sudanese army said Saturday that it repelled an attack by rebels backed by neighboring Sudan outside Malakal, capital of the fledgling country's Upper Nile State.

"It was Sudan-supported militias that attacked SPLA (South Sudan army) positions" around Malakal on Friday, Colonel Philip Aguer told AFP, adding that the South Sudanese army repelled the attack, with an unknown number of casualties.