Sudanese pro-government militia fighters on horesback have killed six people and abducted five in a raid on a village in the Darfur region, rebel leaders said on Wednesday.
But a spokesman from Sudan's armed forces dismissed the accusations of an attack on the village of Dere on Tuesday as "definitely incorrect", saying there was no military or militia activity in north Darfur.
The accusations come at a sensitive time, when Sudan's government is trying to block efforts by the International Criminal Court's prosecutor to put President Hassan al-Bashir on trial for war crimes and genocide in Darfur.
Rebels say attacks by government forces have been increasing and accuse Khartoum of trying to seize potential oil production sites and key transport routes.
Leaders from three insurgent factions said fighters attacked the North Darfur settlement of Bere on horseback on Tuesday, days after a government assault on nearby rebel bases.
Insurgents said the militias were part of a government force that attacked rebel positions in the villages of Disa and Birmaza over the weekend, and was now preparing for new attacks.
International experts say more than five years of fighting has left 200,000 people dead in Darfur and driven 2.5 million from their homes.
Suleiman Marjan, a field commander with the faction of the rebel Sudan Liberation Army (SLA) led by Abdel Wahed Mohamed el-Nur, said the militia attacked Bere early Tuesday morning and killed six people, all civilians.
"They went there to loot and steal camels and cattle. They also took three women and two children," he said by phone from Darfur. He said he did not know why the five were abducted.
The SLA's Unity faction and the insurgent United Resistance Front also reported an attack.
Sherif Harir of the SLA's Unity faction said the militias and government troops in the area were reinforcing.
"They are re-grouping and we are re-grouping. We can not allow them to stay in that area."
A spokesman for Sudan's armed forces on Wednesday said soldiers had been mounting patrols to protect humanitarian convoys in the region, but denied taking part in any attacks.
Up to 400 trade union members demonstrated against the International Criminal Court in downtown Khartoum on Wednesday, the latest in a series of orchestrated rallies in support of the Sudanese president.
Mostly non-Arab rebels took up arms in Darfur in early 2003 accusing the central government in Khartoum of neglect. The Sudanese government, which says the international media has exaggerated the conflict, mobilised militias to quell the revolt.