Rebels in eastern Democratic Republic of Congo killed 10 people, including members of a local aid group, in attacks on vehicles travelling in the province of South Kivu this week, the local government said on Thursday.

Congo's east remains plagued by armed groups eight years after a war that left around five million people dead -- a problem that could weigh on President Joseph Kabila's bid for re-election in a November 27 vote.

Seven people were killed and three injured on Tuesday in an attack on a vehicle owned by a local NGO, Eben Ezer, on a road south of the town of Baraka near Lake Tanganyika, according to local administrator Selestin Kalume Mwanshima.

The same armed group killed three more people when a motorbike was attacked on the same day, Kalume said, blaming the killings on a Congolese rebel band known as Mai Mai Yakatumba.

We are in the process of taking steps to secure the area. It's each day that Yakatumba and its allies, the FNL and FDLR attack civilian vehicles, boats, even entire villages. This must stop, Kalume told Reuters by telephone.

FNL is a Burundian rebel group based in Congo that was blamed for last month's attack on a bar in Burundi in which more than 30 people were killed. The FDLR is a Rwandan rebel group operating in Congo and has carried out numerous atrocities against civilians, including mass rapes.

The United Nations, whose peacekeepers conduct joint operations with Congo's army to fight the rebels, issued a statement calling on the Congolese government to investigate the killings and prosecute those responsible.

We deplore in the strongest terms this attack and all other acts that hinder the work of humanitarian actors in DRC (Democratic Republic of Congo), Pierrette Vu Thi, the coordinator of humanitarian affairs in Congo, said in a statement issued by the U.N. humanitarian affairs office.

Fighting in eastern Congo is often characterised by shifting short-term alliances between different armed groups keen to use instability to control land and resources.

These latest attacks underscore the inability of joint operations by UN peacekeepers and the Congolese army so far to protect civilians from the rebel groups. Kabila's government has vowed to bring the armed groups to heel.

In a speech to launch his re-election bid last month, Kabila said there were no more fires in the east, only embers.