Sudanese warplanes have been bombing rebel positions near Geneina in West Darfur, rebel commanders in the Justice and Equality Movement (Jem) say.
They say there have been several civilian causalities as people flee villages to shelter from the raids.
Correspondents say Jem has claimed a series of recent victories over government troops in the area in fighting which is hampering aid work.
Some 200,000 people in Darfur have died in the five-year conflict.
More than two million people are living in camps after fleeing fighting and continuing insecurity in the region.
The United Nations and African Union have so far sent 9,000 troops for a planned 26,000-strong force.
Prison break
"They killed three citizens - two women and one man," Jem commander Abdel Aziz el-Nur Ashr told Reuters news agency.
Q&A: Darfur conflict
Jem leader Khalil Ibrahim told AFP news agency that bombing raids had taken place on Saturday, Sunday and Monday.
"Residents have been seeking cover from the air strikes under trees and in dry river beds," he said.
International sources confirmed to Reuters that government planes had been seen in action on Sunday.
There has been no confirmation from the Sudanese army about the attacks.
There is concern that insecurity in the region is growing.
"All the roads around Geneina are no-go areas right now," Emilia Casella, spokeswoman for the UN's World Food Programme is quoted by Reuters as saying.
In South Darfur, the AP news agency reports that gunmen have stormed a prison freeing at least 90 prisoners.
Reports say the attackers wounded two guards at the Buram prison and took several inmates with them when they fled in pick-up trucks.
A UN official was quoted as saying the raid appeared to have been carried out by members of the Salamat community, suspected of belonging to the Arab Janjaweed militia associated with the government.
The Sudanese authorities have promised an investigation.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©
~RS~q~RS~~RS~z~RS~52~RS~)