Burundian soldiers, who have been fighting against the M23 rebels in eastern DR Congo, were pulling out following the fall of the city of Bukavu, four sources, including a Burundian army officer and two U.N. officials, said on Tuesday, according to Reuters.

M23 seized Goma, the capital of North Kivu province in eastern Congo, in late January and then took control of South Kivu provincial capital Bukavu on Sunday.

"The Burundian troops are withdrawing from Democratic Republic of Congo. A number of trucks filled with military arrived in the country since yesterday" through a border post, the Burundian army officer said.

ALSO READ: M23 integrates Congolese government soldiers into its ranks

Bukavu city is close to the Burundian border with DR Congo and fighting was reported near Kamanyola border post on Monday and Tuesday.

Burundi has had soldiers in eastern Congo for years, initially to hunt down Burundian rebels there but, more recently, to aid in the fight against M23.

According to estimates, Burundi deployed about 10,000 soldiers to eastern DR Congo to fight alongside the Congolese government coalition which included troops from the Southern African Development Community, European mercenaries and the FDLR, a group linked to the 1994 Genocide against the Tutsi in Rwanda.