The soldiers, who were based in southern Haiti, stand accused of attacking an 18-year-old man in the small coastal town of Port-Salut. Video footage of the alleged attack on a Uruguayan base has been circulated on the Internet.

"I come at this terrible time to offer you and the dear and heroic people of Haiti my apologies for the outrage that some soldiers of my country committed," Uruguay's President Jose Mujica said in a letter released late Tuesday.

"I share your sadness, which I feel as my own," he said, adding that authorities would investigate the matter and apply the "maximum penalty" to those responsible.

Uruguay's defense minister had earlier admitted that the incident had caused "a lot of damage" to the armed forces, which provide around 2,400 peacekeepers worldwide, mostly in Haiti and the Democratic Republic of Congo.

The five peacekeepers accused of sexual assault are to be sent home this week, Defense Minister Eleuterio Fernandez Huidobro said.

The Uruguayan government has opened a case in the matter, as peacekeepers must be tried in their home country for any crimes allegedly committed during their deployments abroad.

Montevideo has also sacked a navy commander with the UN mission in Haiti over the incident.

Haitian President Michel Martelly has condemned the alleged attack and demanded a detailed report on the exact circumstances of the incident, according to his office.

Martelly has also requested a meeting between Haitian officials and UN mission staff so that "measures can immediately be taken to ensure that such acts do not reoccur," his office said in a statement.

On Monday, hundreds of people demonstrated in Port-Salut to demand justice for the alleged victim, while some Haitians have asked for the UN mission -- in the country since 2004 -- to be shut down.

The UN mission -- formed to help maintain peace after chaos erupted at the end of Jean-Bertrand Aristide's presidency -- has also come under fire after a cholera outbreak that could have been transmitted by Nepalese peacekeepers.