South Sudanese and Sudanese forces clashed in a poorly-defined border area on Sunday, the Sudanese military said, the latest outbreak of violence to put a recently signed non-aggression pact into question.

The Sudanese Foreign Ministry described the clashes as a direct and blatant attack on Sudan's sovereignty and security that violated all international norms, and said it would file a fresh complaint at the United Nations Security Council.

Forces from South Sudan and rebels from South Kordofan attacked at 3 a.m. in the area of Baheyret al-Abayd, Sudan's military spokesman Al-Sawarmi Khalid told Reuters.

Fighting is still going on, he said. The government in the South is not abiding by the deal.

Khalid was referring to a non-aggression pact signed by both governments earlier this month, brokered by the African Union to allay fears that rising tensions since the South's secession last July could escalate into war.

In a statement published by the Sudanese state news agency the Foreign Ministry said: We will file a new complaint to the Security Council and the African Union to inform them of the details of the events and demand that they have a role in deterring any assault on the security and stability of Sudan.

In a further sign of continued unrest, the Darfur-based rebel Justice and Equality Movement said it had taken control of Jau, a region claimed by both sides, in a joint attack with forces of the South Sudanese Sudan People's Liberation Movement (SPLM).

Relations between the two countries have plunged after talks failed to halt an oil export dispute, end violence in border areas and resolve other issues relating to the secession.

CLASHES

Juba and Khartoum routinely trade accusations of sponsoring insurgencies in each other's territory. In December, the two armies clashed in Jau, which is close to many of the South's oil fields and abuts the South Kordofan state where Sunday's clashes occurred.

Earlier this month, the Security Council called on Sudan and rebels in areas bordering South Sudan to grant immediate access for U.N. aid workers to the turbulent region.

Fighting has been raging for months between the Sudanese army and rebels from the SPLM-North, which wants to topple the Khartoum government, in the states of South Kordofan and Blue Nile, adjacent to newly-independent South Sudan.

South Kordofan and Blue Nile are home to tens of thousands of fighters who battled Khartoum as part of the southern army during a civil war that ended in 2005. Khartoum accuses Juba of continuing to back the insurgents, which South Sudan denies.

The fighting in recent months has forced about 417,000 people to flee their homes, more than 80,000 of them to South Sudan, according to the United Nations.

(Reporting by Khaled Abdel Aziz; Writing by Dina Zayed in Cairo; Editing by Sophie Hares)