The UN is sending home more than 100 of the 950 Sri Lankan peacekeepers in Haiti, accusing them of sexual abuse, including with underage girls.
Sri Lankan authorities were involved in the investigation
The UN said the troops had paid for sex and that some of the girls were minors.
UN peacekeepers have been involved in a series of sex-abuse scandals, including this year in Ivory Coast, where 800 were suspended.
The organisation said it had a "zero tolerance" policy but it was up to the supplying nations to discipline troops.
A 2005 UN report suggested a central disciplining policy but member nations could not agree.
A total of 108 of the Sri Lankan peacekeepers are being sent home.
The UN Office of Internal Oversight Services and the Sri Lankan authorities had overseen the investigation.
UN spokeswoman Michele Montas said: "The United Nations and the Sri Lankan government deeply regret any sexual exploitation and abuse that has occurred."
She added: "The [soldiers] are back under national jurisdiction. So far Sri Lanka has said... that they are going to be prosecuted in Sri Lanka."
The UN was working to help the victims of the abuse, she said.
Member states are supplying about 100,000 troops to peacekeeping operations worldwide.
In recent years, peacekeepers in Liberia and the Democratic Republic of Congo have also been accused of sexual exploitation.
In July, the UN Special Rapporteur on Torture, Manfred Nowak, said the standards for selecting peacekeepers were too low.
Mr Nowak said concerns about the quality, training and ethics of peacekeepers were growing.