(Correcting spelling of name Maurizio instead of Murizio in paragraph 8 of Aug 21 story) (Adds U.N. comment)
By Opheera McDoom
KHARTOUM, Aug 21 Sudanese forces surrounded and attacked Darfur's most volatile camp on Tuesday to flush out rebels they say are behind recent attacks on police, an army source and camp residents said.
The move on Kalma camp, home to 90,000 people, follows two attacks in the past week on police posts in South Darfur, one near Kalma and the other inside al-Salam camp. One policeman was killed and eight injured.
"At 6 a.m. the government of Sudan moved 2,000 soldiers to surround the camp -- army, police and border intelligence," said Abu Sharrad, a spokesman for Kalma camp.
Sharrad, who called Reuters from inside the camp, said government forces had opened fire but it was unclear if anyone was killed or injured.
"We still cannot tell. They are still surrounding the camp," he added.
An army source said those who attacked the police posts were believed to be in Kalma camp, where rebels have previously taken refuge.
"This is an administrative, organisational operation to restore internal security," he said, adding the army was not involved, only police forces.
The United Nations said it as continuing to monitor the situation. "We are indeed concerned to receive reports of armed activity in the area," said Maurizio Giuliano, spokesman for the U.N. Office for Humanitarian Affairs.
Kalma camp is one of Darfur's most volatile.
Government offices were torched and officials expelled from the camp in 2005. Last year frustrated camp residents rioted, looting an African Union police base in the camps and hacking to death their Sudanese translator.
The 7,000-strong African Union force in Darfur has failed to stem the violence despite a 2006 peace deal. While large-scale fighting has largely ended, rebels and militias have fractured creating lawlessness and uncontrolled banditry.
International experts estimate some 200,000 people have died and 2.5 million driven from their homes since mostly non-Arab rebels took up arms in early 2003.
Khartoum agreed to a 26,000-strong joint U.N.-AU force which will absorb the AU mission and try to stop violence which has hampered the world's largest aid operation in Darfur. Some 500,000 people are out of reach of relief workers.
On Tuesday the U.N. rights office said allied government militias had attacked a village in the central Darfur Jabel Marra region, accusing them of mass rape and abductions which could constitute war crimes.
It called on Khartoum to investigate reports that about 50 women were forced into "sexual slavery" after an attack on the rebel-held town of Deribat last December.
The area is seen as supporting the Darfur rebel Sudan Liberation Army founder and chairman Abdel Wahed Mohamed el-Nur, who rejects a May 2006 Darfur peace deal signed by only one of three negotiating rebel factions.
The U.N. report said a "pattern of mass abduction" which began with the Darfur conflict, appeared to be ongoing. The report covered a six-month period ending in May 2007. (additional reporting by Stephanie Nebehay in Geneva)