By Hez Holland
GOMA, Congo, Oct 28 (Reuters) - The Congolese army prepared on Tuesday to abandon a town in the east of the country as rebels advanced upon it, the army said.
Tutsi rebels loyal to renegade General Laurent Nkunda fought their way along a road towards Rutshuru, about 100 km (60 miles) north of North Kivu's provincial capital Goma on Tuesday, the third day of an offensive launched on Sunday.
"The situation is very serious. It won't be much longer before I have to leave here," said Colonel Delphin Kahimbi, the army's commander of operations in North Kivu, referring to himself and his forces.
U.N. peacekeepers had planned to evacuate around 50 foreign aid workers from Rutshuru but their attempt had been thwarted, Evo Brandau, spokesman for U.N. humanitarian office OCHA, said.
"The army is no longer guaranteeing security," he said.
"The aid workers were not able to leave Rutshuru with the planned convoy. The situation is very tense. They were blocked by both the population and soldiers. There are also attacks on humanitarian installations and looting," Brandau said.
The U.N.'s peacekeeping mission, MONUC, sent attack helicopters against rebel positions north of Goma on Monday, drawing anti-aircraft fire from heavily-armed Nkunda loyalists.
"MONUC will use all available means to protect urban centres including Rutshuru, Sake (to the west of Goma), and Goma," said Michel Bonnardeaux, spokesman for the U.N.'s biggest peace force, with 17,000 personnel based mainly in the east of Congo.
Rutshuru shelters tens of thousands of internal refugees displaced by nearly two years of on-off fighting in North Kivu.
Insurgents attacked Kibumba village, 20 km (12 miles) north of Goma, on Monday, sending around 20,000 refugees fleeing.
An aid worker with medical charity Medecins Sans Frontieres (MSF) told Reuters its staff in Rutshuru could hear explosions from its headquarters at the main hospital early on Tuesday.
"In Rutshuru, the population is fleeing north. We've heard about an evacuation, but for the moment we have no plans to leave," said Axelle de la Motte Saint-Pierre, MSF's deputy head of mission in North Kivu.
"TOTAL PANIC"
"There is total panic in town. The fighting is now around 5 km (3 miles) from Rutshuru," local administrator Dominique Bofondo said by telephone.
U.N. sources said fighting at Kibumba had eased following early morning clashes on Tuesday, and peacekeepers were reinforcing positions there.
Nkunda's National Congress for the Defence of the People (CNDP) accuses Congo's army of collaborating with the Democratic Forces for the Liberation of Rwanda (FDLR), which includes Hutu militias and ex-Rwandan soldiers responsible for orchestrating Rwanda's 1994 genocide of Tutsis and moderate Hutus.
Around 250,000 civilians have fled homes in North Kivu since a January peace deal collapsed in August.
Nearly two years of sporadic fighting had already displaced around 850,000 people before the latest round of fighting began, bringing the total forced to leave home in the province to close to 1 million, according to U.N. figures.
Congo's 1998-2003 war and the resulting humanitarian crisis have killed an estimated 5.4 million.