There were 121 allegations in 2004 compared with 53 allegations reported in 2003, Annan said in a report to the U.N. General Assembly.

Annan said the rise in allegations could be partly due to new measures put in place by the U.N. to encourage alleged victims to come forward.

He added that the figures collected for last year may not reflect the extent of the abuse because some victims may still be unwilling to file complaints.

The vast majority of allegations of sexual abuse and exploitation - 105 out of the total 121 - were leveled at U.N. peacekeepers.

Forty-five percent of allegations against peacekeepers involved sex with minors and 15 percent involved rape or sexual assault. Thirty-one percent involved prostitution with adult women and the rest involved other forms of sexual exploitation and abuse. Allegations against 53 uniformed personnel were substantiated.

Abuses have been reported in peacekeeping missions ranging from Bosnia and Kosovo to Cambodia, East Timor, West Africa and Congo. While allegations of abuse have dogged peacekeeping missions since their inception 50 years ago, the issue was thrust into the spotlight after the United Nations found earlier this year that peacekeepers in Congo had sex with Congolese women and girls, usually in exchange for food or small sums of money.

The remaining charges include: