Thousands of people were fleeing the area 40 kilometres north of Goma in eastern Congo on Monday after rebels attacked and took over a nearby military base. (Karel Prinsloo/Associated Press)

The United Nations sent helicopter gunships into embattled areas of eastern Congo on Monday in an effort to push back rebel forces that had taken over a military base in the province of North Kivu.

The helicopters were firing on rebel forces trying to take over villages near Kibumba, said UN spokeswoman Sylvie van den Wildenberg.

Thousands of people in eastern Congo began fleeing the area on Sunday after fighters of renegade Gen. Laurent Nkunda seized the Rumangabo army base and the headquarters of a refuge that is home to 200 of the world's 700 remaining mountain gorillas.

Civilians were reporting that several soldiers, rebels and civilians had been killed in the heavy fighting.

Nkunda is also vowing to seize the provincial capital, Goma.

Rebel fighters also launched several rockets at peacekeepers' armoured cars Sunday, United Nations officials said.

Many of the 15,000 civilians leaving the area were gathering outside the UN headquarters in Goma and staging protests that accused the 17,000-strong peacekeeping force in eastern Congo of not protecting civilians.

Protesters lobbed stones and rocks over the wall surrounding the Goma headquarters, about 40 kilometres north from where the rebel attacks occurred, on Monday while many more gathered outside three other UN compounds in eastern Congo, UN officials said.

The protesters were damaging cars and shattering windows, van den Wildenberg said.

Peacekeeping officials at one of the buildings fired toward protesters and there may have been some civilian injuries, according to reports.

Meanwhile, the commander of the Congo peacekeeping force resigned on Monday, van den Wildenberg said.

Civilians flee

As civilians fled their homes with livestock and sacks of their belongings, soldiers were also seen fleeing toward Goma in tanks, jeeps and trucks and on foot in what some reports suggested was a major retreat of government forces.

The UN deployed a rapid reaction force on Sunday and appealed to both sides to cease fire at least to allow civilians to escape, van den Wildenberg said.

"But nobody is listening to us and they keep fighting," van den Wildenberg said.

The rebels have said they will only stop if the army ceases first.

It is the second time that rebels have seized the army base since Aug. 28, when rebel leader Nkunda went on the offensive after accusing government troops of violating a January ceasefire.

Nkunda launched a low-level rebellion several years ago, claiming Congo's transition to democracy had excluded the country's minority Tutsi ethnic group, which is being targeted by ethnic Hutus from Congo as well as Rwanda.

Congo's wars began with an insurrection in the east that toppled longtime dictator Mobutu Sese Seko in 1997. A second war broke out a year later, embroiling eight nations in what became a greedy rush for the region's vast mineral wealth. Some 5.5 million have died, most of them from hunger and disease associated with the conflict.

The war ended in 2003 and Congo had its first democratic election in four decades in 2004. But fighting has persisted in eastern Congo.

The UN estimates that more than 200,000 people have fled their homes in the last two months, joining at least 1.2 million displaced in previous conflicts.

With files from the Associated Press