A rebel group in Sudan's Darfur region says government warplanes have bombed its positions in West Darfur.

Leaders of the rebel Justice and Equality Movement, or JEM, say government Antonov aircraft bombed at least two villages on Sunday and Monday near the regional capital of el-Geneina.

The group says the attacks targeted JEM positions involved with a recent rebel push into the area.

The Sudanese military has not confirmed the bombing.

The United Nations says the latest violence in Darfur is hampering efforts to bring international aid to the troubled region.

Last week, Sudanese soldiers attacked a supply convoy of the new joint UN-African Union peacekeeping mission in Darfur. Sudan later said the attack was the result of a mistake.

Earlier this week, a group of armed gunmen stormed a prison in South Darfur, freeing at least 90 prisoners. It is not clear who the detainees were or why they were in prison. Authorities are investigating.

Five years of fighting in Darfur has claimed the lives of some 200,000 people and displaced more than 2.5 million others.

The fighting broke out in early 2003 when local rebels took up arms against the Arab-led Sudanese government, saying Khartoum had neglected their region.

Some information for this report was provided by AFP and Reuters.