At least 24 people, including civilians, rebels and soldiers have been killed in fighting near Bujumbura, the capital of Burundi.

More than 7,500 civilians fled to nearby hills when the army chased rebels of the Hutu dominated group, the National Liberation Forces (FNL) who had ambushed an army patrol.

The FNL has not signed the ceasefire agreement reached earlier this month by the government and the main Hutu rebel movement, the Forces for the Defence of Democracy (FDD).

A BBC correspondent in Bujumbura says that rebels belonging to the FNL and to a branch of the FDD which was not a signatory of the agreement, are believed to be stocking up for more fighting after they stole more than 300 heads of cattle at the weekend.

More than 300,000 people, mainly civilians, have been killed in the nine-year civil war in Burundi.

'Shot dead'

At least 19 people, including 13 rebels, four soldiers and two civilians have been killed since Sunday as a result of the ambush against the Tutsi-dominated army in Mwico, southeast of Bujumbura, an army spokesman was quoted as saying by the French news agency, AFP.

In a separate incident, three civilians were killed and three others injured when FNL rebels ambushed four buses northwest of Bujumbura on Saturday, according to witnesses.

The army is dominated by ethnic Tutsis

The FNL has denied the accusation.

Two civilians, including a local official, were also reported killed at the weekend by rebels in the northwestern province of Bubanza.

"The FNL came at night. They made Barthelemy Semajeri, who is responsible for the Rugunga sector, as well as a dignitary, get out of their homes and they shot them dead after tying them up," a local official told AFP.

The agency says that more than 20 local officials have been killed in Burundi since the beginning of the year.

A truce has been in place for 10 days, but the ceasefire signed by the FDD rebels and the government will only be effective from 30 December.