Some 1,000 security men had on Tuesday, between 5:00 a.m. and 6:30 a.m. (03.00 – 04.30 GMT), surrounded Soba Eradi camp, 30 km south of the capital, Khartoum, sources said. Using loud speakers, they announced their intention to enter the camp, conduct arrests and locate confiscated firearms.

"They said they needed to know who killed the police, who took the guns," Karak Mayik Nyok, executive director of the local women’s group Diar for Rehabilitation and Development Association (DRDA), told IRIN on Wednesday. "They needed to know who were behind the unrest."

During the search, she added, the IDPs sought refuge inside their homes in fear of the beatings that were reportedly taking place.

"They beat up a lot of people, especially women, and I heard they arrested about 70 people, but I don’t know the exact number," Nyok said.

At a news conference on Tuesday, Jan Pronk, the UN Secretary-General’s representative in Sudan, said: "The situation has not improved, far from it. It is very important that all sides show maximum restraint to prevent further escalation and loss of life. Too many people have been killed on both sides."

"Restoration of law and order is necessary," he continued. "Police have the right to arrest civilians if they have a good suspicion that they carried out an illegal act, but it is very important that those arrested be treated according to the law."

On Tuesday, the official Sudanese News Agency quoted Mutrif Sideeq, undersecretary in the Ministry of Foreign Affairs, as saying the incident was "regrettable" - but the undersecretary also pointed out that "aggression on police is an aggression on the state."

Fighting broke out in the camp on 18 May when security officers tried to forcibly relocate the IDPs from the area. At least 30 people - 14 policemen and more than 20 IDPs - were reportedly killed.

Sources said that trucks loaded with armed men rolled into Soba Eradi, a camp housing 26,000 people, at 5 a.m (0300 GMT). The IDPs, who refused to be moved, gathered at a local bus station to protest. At about 9:40 a.m (0740 GMT), the police opened fire on them.

"The fighting started when a policeman - maybe by accident, we don’t know - shot and killed a child of 14 years old," Nyok said.

The situation, she added, escalated when the father of the child drove a car into a police-station building. The angry crowd then stormed the building, killing eight policemen and freeing the prisoners from their cells.

The IDPs also reportedly confiscated weapons from the security forces. Hundreds then fled the area as unknown assailants set fire to the police station and IDP shelters.

The IDPs had lived in Soba Eradi since the 1980s, but the Sudanese government started destroying their homes in August 2004.

The government said the demolitions were part of a larger replanning programme that was meant to provide plots for the IDPs and bring them vital services such as electricity and water.

The UN Office for the Coordination of Humanitarian Affairs said that in the past the Sudanese authorities had forcibly relocated IDPs without making prior preparations to ensure the new location was fit for human habitation.

According to a May 2005 rapid assessment report on health and nutrition in IDP settlements in Khartoum State – published by the Khartoum State Ministry of Health, the World Health Organisation and the UN Children’s Fund (UNICEF) - an estimated 325,000 IDPs are living in four official camps. Approximately 1.5 million more are scattered throughout various squatter and peripheral areas.