The UN says it will investigate allegations that some peacekeepers in southern Sudan have been involved in the rape and sexual abuse of children.
The UN has investigated over 300 peacekeeping personnel worldwide
British newspaper the Daily Telegraph said the abuse began shortly after the UN mission arrived in March 2005.
It quoted an internal report by UN children's agency Unicef and cited interviews with 20 alleged victims.
The UN has more than 10,000 police, peacekeepers and staffers from over 70 countries in southern Sudan.
They are there to enforce a peace agreement that ended a 21-year civil war in the region.
'Ascertain the facts'
The daily says that UN personnel in the regional capital, Juba, have been having sex with children as young as 12.
It has gathered accounts from more than 20 people who say they have been abused.
It also cites an unfinished internal Unicef report which, it says, suggests the UN has been aware of the problem for over a year.
UN Assistant Secretary General for Peacekeeping Jane Holl Lute said the allegations would be investigated.
"I do not believe these are new allegations," she told the Associated Press news agency. "Nevertheless, we will treat them as seriously as we treat all other allegations."
"We need to ascertain the facts and follow it through to appropriate resolution and take action if necessary," she said.
There have been allegations of sexual abuse by UN peacekeepers in places such as DR Congo, Haiti and Liberia.
Last month, former UN Secretary General Kofi Annan said there would be "zero tolerance" of sexual exploitation by peacekeepers.
The UN says it has investigated abuse allegations against 316 of its personnel since January 2004, 179 of whom have been disciplined.