A United Nations peacekeeper and three Congolese troops were killed by rebels backed by Uganda, as fighting broke out in the Democratic Republic of the Congo.
The Congolese government has been trying to re-establish its authority in the region ahead of next year's general elections, after the Congolese people voted to approve a new constitution in the country's first ballot in 40 years.
The latest battles were part of an attempt to drive the rebels out of their camps in the eastern Congo's forests. Thirty five of the rebels are also thought to have been killed in the fighting, where 3,500 Congolese troops, supported by 600 UN peacekeepers using helicopter gunships went on a week-long offensive.
Last Saturday, 200 Nepalese peacekeepers and 1,500 government troops captured the rebel held town of Nioka, in the Ituri district.
The Congo is still recovering from a five year civil war that killed four million people and drew in the armies of six neighbouring countries. Some of the militias that fought in the war are still active in eastern Congo, and receive backing from Rwanda and Uganda.
UN spokesman Hans-Jako Reichen said there are about 1,000 Ugandan-supported militias in the DRC, running guns, poaching endangered wildlife and terrorising civilians.
The Congolese government is determined to improve internal security ahead of next June's parliamentary and presidential elections, especially in the mineral-rich eastern province. It will be the first election for a democratic government which is to replace a transitional administration set up after the war. Last week, millions of Congolese voted in a referendum on a constitution.
In the past six years, the UN has sent 17,000 troops - the biggest peacekeeping force in the world - to help provide security in the region. 60 UN peacekeepers have been killed since the UN mission to the Congo began.