Government forces have also painted their military vehicles in the white colors of the African Union cease-fire monitors "in violation of all established norms and conventions," the chief African Union envoy to Sudan, Ambassador Baba Gana Kingibe, told a press conference in the Sudanese capital on Saturday.

Kingibe gave four instances of Sudanese army troops conducting what he called "coordinated offensive operations" with the Janjaweed Arab militia since Sept. 18 in Darfur.

His charge is politically embarrassing to the new government as Sudan has repeatedly denied any collusion with the Janjaweed, which has been blamed for the bulk of human rights violations in the two-year conflict.

More than 180,000 people have died in Darfur and another 2 million people have been displaced since residents of African ethnic origin rebelled against the government, accusing it of neglect and discrimination.

It is rare that the African Union directly apportions blame for the fighting in Darfur. Normally it takes pains to call for restraint from both sides.

Kingibe said the latest escalation in fighting began with attacks by the rebel Sudan Liberation Army in late August that continued through September. Initially the government forces showed restraint and managed to stop the Arab militia from attacking the SLA.

But the regular army "suddenly decided to abandon such responsible behavior and posture and resorted to the violent destructive and overwhelming use of force not only against the rebel forces, but also on innocent civilian villages and the Internally Displaced People's camps," Kingibe said in a prepared statement.

On Sept. 18, the army and Janjaweed attacked the settlements of Khartoum Djadeed, Sandego, Khasantongur, Tary, Martal and Djabain. The raids killed 12 people, seriously wounded another five, and displaced about 4,000 civilians, Kingibe said.

On Wednesday Sept. 28, government and Janjaweed forces attacked the Aro Sharow camp for displaced people and the villages of Acho and Gozmena, resulting in the death of 32 people, with another seven missing, and the looting and burning of about 80 homes.

During this attack, Kingibe said, "reportedly 400 Janjaweed Arab militia on camels and horse back went on the rampage" while government helicopter gunships flew overhead.

On Thursday, government troops and police raided the town of Tawilla and the adjacent camp for displaced people in North Darfur.

"The government of Sudan forces used approximately 41 trucks and 7 land cruisers in the operation, which resulted in a number of deaths, massive displacement of civilians, and the destruction of several houses in the surrounding areas as well as some tents in the Internally Displaced People's camps," Kingibe said.

Some of the government vehicles were painted in the white color of the African Union mission.

"During the attack, thousands from the township and the IDP camp, and many humanitarian workers, were forced to seek refuge near the African Union camp," he added.

On Friday, the African Union received reports of ground forces attacking Sheiria, a town of 33,000 people in South Darfur, and helicopter gunships dropping bombs on the nearby village of Ato. The African Union is investigating the extent of casualties and damage, Kingibe said.

"If the government of Sudan forces claim that their latest acts of cease-fire violations are in retaliation for earlier acts of provocation by the SLA, this cannot be justified given the deliberately calculated and wanton destruction wrecked by the disproportionate use of force on innocent civilians and IDPs in their camps," he said.

"Whatever the circumstances, we expect a greater sense of responsibility and a greater standard of behavior on the part of the government of Sudan troops, and their allies, than they have exhibited in the last 4 days," he added.

Kingibe said he was calling on the government, as he had earlier called on the rebels, to immediately abide by the cease-fire that was proclaimed in Darfur last year.

He also called on the government to stop the "unethical practice" of painting its vehicles in the African Union color.