The UN envoy to the Democratic Republic of Congo has urged support for the government in its battle with Rwandan rebels, despite accusations of abuses.

Former Nigerian President Olusegun Obasanjo said an army offensive had achieved "reasonable success".

Last week, the UN mission withdrew its support for government army units implicated in killing civilians.

Mr Obasanjo said the seriousness of the humanitarian situation could not be downplayed, but a solution was needed.

Mr Obasanjo told the UN Security Council that "the slide to war that threatened the region last year was effectively reversed".

But he said that while the symptoms had been dealt with, there were "underlying ailments" in eastern DR Congo.

"Without dealing effectively with the underlying issues, peace can neither be durable nor irreversible," he said.

The Rwandan Hutu FDLR rebels have been at the heart of years of unrest in the region.

Their leaders fled to the area in 1994 after being accused of taking part in Rwanda's genocide and have since been fighting with the local Tutsi population and government troops.

Mr Obasanjo was appointed last year after Tutsi rebel leader Laurent Nkunda seized new territory, leaving some 250,000 people homeless.

He said he was fighting to protect his community from attack by Rwandan Hutu rebels, but he was arrested by Rwanda who after years of mistrust began to work with DR Congo against the FDLR.

Mr Obasanjo said this rapprochement in relations between DR Congo and Rwanda gave him hope, saying this time last year the countries' two president would not shake hands or speak to one another.

In its crackdown on the rebels, the Congolese army has been accused of targeting thousands of Hutu civilians.

Aid agency Medecins Sans Frontieres (MSF) alleged last week that its vaccination clinics were being used as "bait" for civilians in the North Kivu region.