The rights group said it interviewed women from Makeni, Port Loko, Lunsar, and the Yelibuya Peninsula who gave detailed accounts of rape, including a significant number of cases of gang rape and rape of young children as young as 10 years old.

In many cases, victims were taken to rebel bases or command centres and raped there, suggesting that this is a sanctioned behaviour, it added.

"Our research has uncovered a disturbing number of cases of rape by RUF fighters in the town of Makeni and other areas under their control," Peter Takirambudde, executive director of the Africa Division of Human Rights Watch, said.

"Women in RUF-controlled areas are at constant risk of being abducted and raped. Once again this underlines the need for the protection of civilians to be the first priority of international and government troops in Sierra Leone," he added.

In early May, the rebels took more than 500 UN peacekeepers hostage and restarted offensive action against the Sierra Leone government.

Eyewitnesses and survivors who have fled rebel-controlled areas have provided detailed accounts of widespread looting, rape, abduction, killings and mutilations by the rebel forces in recent weeks.

Human Rights Watch has called upon the members of the UN Security Council to provide the UN mission in Sierra Leone with the mandate and means to protect civilians from atrocities.

The group has also called on the council to instruct the UN mission to begin investigating current and past abuses against civilians by the rebels and other forces.

This material would be used for prosecutions of those alleged to be responsible for gross violations of human rights and the laws of war in Sierra Leone, it added.