United Nations agencies suspended some relief operations in Congo's conflict-torn North Kivu province on Friday, and renewed fighting involving rebels threatened refugee camps and food distribution, officials said.

Three months after Democratic Republic of Congo's government signed a peace deal with rebel and militia groups in the violent east, humanitarian workers report insecurity is still badly hampering their efforts to help thousands of displaced people.

The U.N. refugee agency UNHCR halted its activities in camps near the village of Kinyandoni, 75 km (47 miles) north of the North Kivu provincial capital Goma, after an army patrol clashed with Rwandan Hutu rebels on a looting raid nearby.

"It's really for security reasons. We will wait until the situation calms down, since the clashes were nearby," Francesca Fontanini, spokeswoman for UNHCR in Congo, told Reuters.

In another incident on Thursday, U.N. peacekeepers were caught in the crossfire when fighting between Tutsi insurgents and local Mai-Mai militia broke out around the village of Mashango, 85 km (53 miles) northwest of Goma.

The conflict in the eastern province, which pits Congolese Tutsi insurgents against Rwandan Hutu FDLR fighters and also involves the army and other militia groups, has its roots in neighbouring Rwanda's 1994 genocide in which Hutu militants slaughtered around 800,000 Tutsis and moderate Hutus.

The U.N.'s World Food Programme (WFP) was forced to call off a distribution mission in the area on Friday after U.N. peacekeepers, part of the 17,000-strong U.N. mission in Congo (MONUC), cancelled their military escort due to the deteriorating security situation.

The Jan. 23 peace accord signed in Goma by rebel and militia groups was aimed at ending years of violence in Congo's lawless east, which has raged on long after the official end of a 1998-2003 war. Nearly a half million North Kivu residents fled on-and-off fighting throughout 2007.

The east Congo peace process has been plagued by daily ceasefire violations, and there are now 75,000 more internal refugees than before the peace pact was signed.

"We'd hoped that some people would be going home, but instead there are more and more ... 550,000 displaced in 78 sites. It's a logistical nightmare in terms of security," said Aya Shneerson, the head of the WFP's mission in North Kivu.

At least 16,000 people in North Kivu have fled since the weekend from intensifying clashes between the army and fighters of the Democratic Forces for the Liberation of Rwanda (FDLR).

Experts say 5.4 million people have perished in Congo's 1998-2003 war and the resulting humanitarian disaster, most from hunger and disease linked to the conflict. The continuing crisis in the vast, former Belgian colony, makes it the world's most deadly conflict since the Second World War.