"Until now we have counted at least 17 civilians killed," he said.
Jar el-Neby, a rebel commander from the rival Sudan Liberation Movement (SLM), also accused the government of bombing.
"They bombed for about five hours [on Saturday]," he said. "I think they are trying to stop our commanders' conference."
Omar Hassan al-Bashir, the Sudanese president, has agreed not to attack the rebels during their conference but the African Union has twice accused the government of bombing rebel positions.
A Sudanese army spokesman was not immediately available to comment.
The government regularly denies bombing in Darfur which would be a violation of ceasefire agreements and UN Security Council resolutions.
Rebel commanders want to hold a conference in Darfur to unite their positions before peace talks. There are more than a dozen rebel factions.
Rebels say they want guarantees the army will not attack or bomb their meeting.
Only one of three rebel negotiating factions signed a peace deal in May, which tens of thousands of Darfuris have rejected because they want more political representation, compensation for war victims and guarantees that militias allied to the government will be disarmed.