UNITED NATIONS (AP) -- The United Nations, Haiti and Uruguay are investigating allegations that U.N. peacekeepers from Uruguay sexually abused an 18-year-old Haitian man, the United Nations said Tuesday.

U.N. deputy spokesman Eduardo del Buey told reporters that the five alleged perpetrators have been confined to barracks pending the outcome of the three investigations.

The alleged attack occurred on July 20 but only became public last week when a video taken by cell phone was circulated and the U.N. announced an investigation. The Uruguayan military has called the incident at the peacekeepers' base in Port-Salut on Haiti's south coast a prank that got out of hand and says a preliminary U.N. investigation shows no evidence of rape.

“If the investigations prove that the allegations are true,” del Buey said, “we would expect that these people be prosecuted in the full extent of the law.”

In a statement Sunday, the Uruguayan defense ministry said a U.N. preliminary investigation had found that the men did not sexually abuse the Haitian teen but that they committed misconduct by allowing a civilian into their barracks and could face severe penalties.

The video of the encounter is clearly sexual in nature. However, a U.N. spokeswoman in Haiti, Eliane Nabaa, said the U.N. had not come to any conclusions -- a view echoed by del Buey who said “we are waiting to see what the outcome of the investigations are.”

Dr. Clifford Gauthier, a physician who examined the young man a month after the alleged attack, told the AP in Haiti that he found evidence that was consistent with signs of sexual abuse even five weeks after the attack. He said he asked the young man why he waited so long for treatment and didn't get an answer.

While allegations of abuse have dogged U.N. peacekeeping missions since their inception over 50 years ago, the issue was thrust into the spotlight after the United Nations found in early 2005 that peacekeepers in Congo had sex with Congolese women and girls, usually in exchange for food or small sums of money.

The U.N. peacekeeping department instituted a “zero tolerance” policy against sexual abuse, a new code of conduct for its more than 110,000 peacekeepers deployed around the world and new training for officers and all U.N. personnel. Nonetheless, allegations of sexual abuse persist in Congo and elsewhere.

The United Nations doesn't have the authority to prosecute those accused of sexual abuse but it has urged countries that deployed the troops to pursue legal action against alleged perpetrators.

“We're very gratified with reports that we got from the Uruguayan Defense Ministry that they would take appropriate action if the allegations are proven to be true,” del Buey said.

Haitian President Michel Martelly has “vigorously condemned” the alleged assault of the young Haitian, calling it an “act that revolts the national conscience.” Several hundred Haitians demonstrated in Port-Salut on Monday, calling for reparations for the young man.

The allegation threatened to worsen the reputation of the U.N. in Haiti which is viewed by many Haitians as an occupying force. Many Haitians are still angry over a cholera outbreak that was inadvertently brought to the country by peacekeepers from Nepal last year.

Del Buey was asked whether in light of the video, the U.N. was retracting its statement on Aug. 18 that the allegations of sexual abuse were unfounded.

“It's not being retracted,” he said. “We did not comment on the video because ... we didn't know where the video came from, who took it. We don't have a sort of chain of evidence to show that the video was bona fide.”

“That video is now part of the court case that the family is bringing against the Haitian prosecutor, and the family is bringing against the five perpetrators. So the video is something that we would not like to comment on because it is evidence in an ongoing investigation,” he said.