Speaking during a short visit to Freetown, President Obasanjo said he could not see how the troops could be withdrawn at the moment.

He said they would be needed to cement peace, despite rebel calls for them to be pulled out.

Around 10,000 Nigerian troops are in Freetown at the head of an Ecomog peace-keeping force.

President Obasanjo touched down in Freetown en route to Lome in Togo where talks aimed at securing peace in Sierra Leone are now in their fourth week.

"Within a week, I believe Sierra Leone will start living in peace and I am optimistic about that peace," he said.

Human rights abuses

Meanwhile, the United Nations Human Rights Commissioner Mary Robinson - who has also been in Freetown - has said the scale of human rights abuses in Sierra Leone is greater than in Kosovo.

She said the international community must act to stop the killing and torture.

Mary Robinson: "Girls as young as 10, 11 and 12 have been raped"

During her visit, streets were thronged with displaced civilians who had fled rebel atrocities in rural areas.

Many of them showed terrible wounds or had limbs hacked off.

Mrs Robinson said she wanted to emphasise the need for justice and stressed that her visit was not a one-off trip but part of a greater commitment to Sierra Leone by the international community.

She said it was for others to judge whether the world was exercising double standards by reacting firmly to Kosovo, while paying less attention to Sierra Leone.

"Worst in world"

Mrs Robinson's visit coincided with a report saying atrocities committed in Sierra Leone were among the worst violations of human rights in the world.

New York-based Human Rights Watch said entire families had been gunned down in the street by rebels, children and adults had been mutilated with machetes, and girls were taken to rebel bases and sexually abused.

The report contains eyewitness accounts of mass murder by the rebels and systematic, organised rape.

One witness saw a female rebel commander forcibly inspecting girls to see if they were virgins, and then handing them over to the rebels who raped them

International apathy

Human Rights Watch Corrine Dufka tells of execution and amputation units

Human Rights Watch said the widespread violations in Sierra Leone had been largely ignored by the international community.

"This is not a war in which civilians are accidental victims," Peter Takirambudde, executive director of the Africa division of Human Rights Watch, said in a statement.