Clashes erupted in Abyei Wednesday between north and south Sudanese troops, the southern army said, just days after a deal to demilitarize the disputed area, and as Khartoum stepped up air strikes in neighboring South Kordofan.

Members of the Sudanese Armed Forces (SAF -- northern army) exchanged fire with the Sudan People's Liberation Army at the Kiir, or Bahr al-Arab, river, the southern army's spokesman told Agence France Presse, without providing details of casualties.

President Barack Obama is calling on Sudan's warring factions to end the bloody violence threatening a peace agreement as the south gears up for independence due in three weeks.

"There is no military solution," Obama said in an audio message recorded late Tuesday for the U.S.-funded Voice of America (VOA) broadcasting network.

Sudan's army has launched repeated air strikes on the southern army in Unity state in a bid to seize oilfields there weeks before the south's independence, a southern army spokesman said Friday.

Philip Aguer, spokesman for the Sudan People's Liberation Army (SPLA) of the south, said the SPLA was on "maximum alert" and strengthening its defensive positions, fearing the start of an invasion to seize the oilfields.

The United States called Tuesday for clashes in Sudan to "cease immediately," expressing concern over reports of several fatalities in the fighting between the northern and southern armies.

Washington is "deeply troubled" by United Nations reports that six people have been killed in the fighting in Kadugli, capital of volatile South Kordofan state, State Department spokesman Mark Toner told reporters.

The United States called Wednesday on Sudan's northern and southern leaders to meet immediately to defuse a crisis over the disputed Abyei border region and help save a 2005 peace agreement.

Johnnie Carson, the top U.S. diplomat for Africa, renewed U.S. condemnation of the May 21 seizure of Abyei by troops serving the northern-based government of President Omar al-Bashir and repeated American calls for them to withdraw.

Sudan’s flashpoint town of Abyei was ablaze on Monday with gunmen looting properties after its capture by northern troops, the United Nations said, as Washington demanded Khartoum pull out its forces.

The U.N. Mission in Sudan, or UNMIS, warned Khartoum it was responsible for law and order amid reports thousands of civilians were fleeing southwards after northern Sudan Armed Forces troops and tanks overran the border town Saturday.

North and south Sudan have agreed to start withdrawing unauthorized troops from the flashpoint Abyei border region, the United Nations said, a week after clashes there left 14 people dead.

The two sides agreed that the pullout would begin from Tuesday and be completed within a week, the U.N. Mission in Sudan (UNMIS) said in a statement late on Sunday.

Clashes between south Sudan's army and rebel militiamen killed at least 55 people, a government official said Sunday in the soon to be independent state gripped by a bloody wave of unrest.

The fighting raged for about three hours on Saturday in Jonglei state between the southern Sudan People's Liberation Army (SPLA) and gunmen led by former militia leader Gabriel Tang, also known as Tang-Ginye.

Iran has smuggled more weapons to Hizbullah, Syria, and Palestinian groups in recent months, taking advantage of the wave of unrest in the Middle East, reported the Israeli newspaper Haaretz on Friday.

Because international attention is focused mainly on regime changes and local intelligence services are busy protecting their rulers, the Iranians have been able to act with greater impunity, it said

Sudanese Foreign Minister Ali Ahmad Karti accused Israel on Wednesday of carrying out an airstrike a day earlier on a car on Sudan's Red Sea coast that killed two people.

Karti's charge came as a number of Israeli newspapers spoke of the same thing, but the Israeli military and foreign ministry both declined to comment.