William Lacy Swing, the Special Representative to the UN Secretary General in the Democratic Republic of Congo, told the Financial Times on Sunday that an ongoing investigation into the allegations would be “thorough” and that strict disciplinary measures would be taken to ensure such abuses do not recur, if the allegations prove founded.

The future of UN peacekeeping operations are being discussed at a special meeting of the Security Council on Monday. One of the UN’s hitherto most successful missions in Africa - policing the border conflict between Ethiopia and Eritrea - is already undermined by similar allegations of sexual abuse, including claims that UN soldiers were involved in paedophilia and pornography.

“We are trying to deal with this issue thoroughly, seriously and with all transparency,” Mr Swing said. “We are determined to be highly professional and above reproach. If there is anything in this we will be very firm on it. We have a huge and very important task to accomplish here.”

The UN has over 10,000 troops in Congo, supporting a fragile transition from what was Africa’s single most deadly war, in which over 3m people are estimated to have died, many from hunger and preventable disease.

UN officials in Congo said the claims of sexual abuse surfaced in January and involved members of a Uruguayan peacekeeping contingent who were allegedly exploiting underaged girls at an internally displaced camp in Bunia, the provincial capital of the troubled province of Ituri. One of the girls involved had been raped repeatedly in the past by Congolese militia.

Preliminary UN investigations showed that the abuse may have been much more widespread than initial claims, involving Uruguayan, Nepalese and Moroccan peacekeepers and possibly others including civilian UN personnel. Girls involved were between 12 and 15 years old.

Quoting from an internal UN cable, one UN official said that “abuse had been taking place in private and abandoned houses, fields, bushes and churchyards.”