Washington  - The United States Saturday condemned an attack by Sudanese rebels near Khartoum and warned the aggression threatened efforts by the international community to resolve the country's conflicts.

Sean McCormack, spokesman for the US Department of State, said the attack was made by Justice and Equality Movement (JEM) forces in the area of Omdurman, near Khartoum.

"We call for an immediate end to fighting. These actions undermine the ongoing efforts of the international community to support resolution of the conflicts in Sudan," McCormack said in a statement.

JEM is a key player among the rebels in western Sudan's troubled Darfur province, where an estimated 300,000 people have been killed by government-backed militia and by rebels since early 2003. More than 2 million people have been displaced in the fighting.

The US implored both JEM and the Sudanese government "to guard against attacks against civilians in Omdurman and Darfur" and warned "both sides against taking any retaliatory action based on ethnicity or tribe."

January's deployment of the joint UN-African Union peacekeeping operation in Darfur, known as UNAMID, has been slow, the UN was recently told. The force still lacks operational capabilities, attack helicopters, military engineers and logistical support.

Only 40 per cent of the authorized 20,000 military personnel had been deployed as of late April, and it is expected to take at least another year to complete the military deployment.

Once UNAMID is fully deployed with civilian and police components, the force will be the UN's largest peacekeeping operation in the world at more than 30,000 personnel. (dpa)