Militias backing Sudan's government have killed at least 63 people in attacks in Darfur in the past week, African peacekeepers say.
The Janjaweed are accused of ethnic cleansing
At least 27 of the victims are thought to be children under the age of 12.
The attacks were on camps for the displaced in the rebel stronghold of Jebel Moon, in West Darfur.
The government says it is disarming the Janjaweed militia but a BBC correspondent in Sudan says all the evidence points to the exact opposite.
United Nations Secretary-General Kofi Annan has urged the Sudanese government to restrain the militias following the attacks.
Militia wearing government uniforms, on camels and horseback, swept into eight villages and camps in Jebel Moon on 29 October.
The African Union (AU) investigation team has just returned from the area to make its report.
The area is a stronghold of the National Redemption Front (NRF) alliance, one of the Darfur rebel group which refused to sign up to a peace deal in May.
"The government have begun mobilising the Janjaweed widely, especially in West Darfur, because they want to clear the area and move north along the border and defeat us," said the NRF's Bahr Idriss Abu Garda.
The BBC's Jonah Fisher in Darfur says that all along the long border with Chad, villagers are fleeing terrified as the Janjaweed aggressively take up positions in key towns.
Three years ago, at the start of the Darfur crisis, the Janjaweed cleared hundreds of villages, displacing more than two million people.
With morale in the Sudanese army reported to be low, Khartoum seems to have turned once again to their most brutal of allies, our correspondent says.
Some 200,000 people have died in Darfur, with the Arab Janjaweed accused of ethnic cleansing against black Africans.
Sudan's government says the scale of the problems has been exaggerated and resists plans for the United Nations to take over the peacekeeping force from the AU.