Hundreds of thousands will be affected by fighting as a result of the planned intervention

Tens of thousands of civilians in the Democratic Republic of Congo are expected to flee their homes as a result of a planned offensive by United Nations and Congolese government forces against Rwandan Hutu rebels in the east of the country.

The UN’s Office for the Co-ordination of Humanitarian Affairs (OCHA) has warned that at least 368,000 people in North Kivu province and 118,000 in South Kivu will be affected by fighting as a result of the planned intervention that was authorised on Thursday. A further 90,000 could be affected as rebel fighters flee west into Oriental province.

The warning comes amid reports from the UN that humanitarian aid workers are dangerously overstretched in the DRC, an area which has suffered from violent ongoing conflict for more than two decades.

Planning documents released by the OCHA say that the offensive is likely to “quickly overwhelm” the country’s “weak local capacity” and that local aid resources are likely to be highly inadequate.

A joint operation to disarm rebel forces in eastern Congo was authorised by the UN Security Council after thousands of Hutu rebels failed to meet a deadline of 2 January to disarm themselves and surrender. The 15 member nations agreed unanimously that the rebels must leave the area “immediately”.

Thousands of civilians were targeted by the FDLR rebels when the UN staged its last major offensive in eastern DRC in 2009, causing concern for the safety of village communities should the latest operation go ahead. Last week, UN and government troops attacked Burundian rebels in the east of the country as part of a preparatory operation.

Martin Kobler, the UN envoy in DRC who briefed the Security Council by video conference last Monday, has not yet said when the offensive will take place, but it is due to be discussed by African leaders at a summit in Angola on 15 and 16 January.

Following last week’s “preparatory operation” against Burundian rebels, about 1,400 Hutu fighters are thought to remain in the area, placing pressure on the UN and Congolese joint forces.