Thousands of civilians fled heavy fighting in Democratic Republic of Congo's (DRC'S) troubled North Kivu province after clashes erupted before dawn on Thursday between government forces and renegade soldiers.

Some 1 000 fighters loyal to rebel Tutsi General Laurent Nkunda attacked a Congolese army brigade headquarters in Katale, around 60 km northwest of the provincial capital Goma, at around 04h00 (02h00 GMT), witnesses said.

"It was another attack by the insurgents," Colonel Delphin Kahimbi, army operations commander in North Kivu, told Reuters.

"We are taking steps this time to finish with this situation, which is beginning to make us look ridiculous," he said.

Army officials declined to give casualty figures but a witness in Masisi, a nearby town of more than 10 000 residents, said several civilians had been hit by stray bullets and that the population there had fled.

"Masisi has completely emptied of all inhabitants. They've all run away," Jean Kugaya, an aid worker with the relief agency World Vision, told Reuters.

The United Nations refugee agency (UNHCR) said it could not confirm Thursday's displacement but said it was worried by a jump in the number of internal refugees in recent weeks.

"We fear that with these increasing confrontations there will be more and more displacements, creating more (refugee) sites, and they will become increasingly difficult to manage," UNHCR spokesman Jens Hessemann said.

WAR FEARS

In 2004, Nkunda led two army brigades, around 4, 00 men, into the bush and briefly captured Bukavu, the capital of neighbouring South Kivu. He faces an international arrest warrant for war crimes allegedly committed at the time.

President Joseph Kabila promised to bring peace to the east of Congo after last year winning the first democratic election in more than four decades, a vote meant to draw a line under a 1998-2003 war that killed an estimated 4-million people.

Thousands of Nkunda's fighters were brought into special mixed brigades within the army as part of a January truce brokered by neighbouring Rwanda.

But violence has continued and those fighters began abandoning their positions last week.

The troop movements, carried out without the blessing of government commanders, sparked fears of a return to war in the east, a stronghold of militias and foreign and domestic rebels.

At least five government soldiers have been killed in fighting since the split, but there had been hope that, after meetings earlier this week between army officers and Nkunda's commanders, the violence had ended.

"This is a very serious and obvious lack of respect for the commitment made by the pro-Nkunda elements (within the mixed brigades)," said spokesperson in North Kivu for the country's 17 000-strong UN peacekeeping mission Sylvie Van Den Wildenberg.

The UN World Food Programme estimates at least 200 000 people have been displaced by violence related to Nkunda's fighters since the beginning of the year.