Former Haitian Prime Minister Yvon Neptune. AFP FILE PHOTO

The UN Stabilization Mission in Haiti (MINUSTAH) welcomed the release and said Neptune, in his 60s and whose health deteriorated in prison, was being treated by medical staff.

"MINUSTAH has for some time been concerned at the prolonged detention of Mr. Neptune, and has made its concerns known at the highest levels of both the Transitional Government and the current government," the mission said in a statement.

"The state of Mr. Neptune's health, which declined dramatically during his time in prison, remains a serious preoccupation and he is currently under the care of medical staff serving with the United Nations in Haiti, where he will remain until he is well enough to return to his family," it said.

Neptune, who was prime minister from 2001-2004, had been implicated in the massacre of some 50 opponents to Aristide in the western port city of Saint-Marc two weeks before Aristide tumbled from power in February 2004.

Former Haitian Prime Minister Yvon Neptune (C - blue shirt) is escorted and guarded by UN peacekeeper 27 July, 2006, as he is taken from a Port-au-Prince prison to a hospital on a UN ambulance. AFP PHOTO

An armed rebellion forced Aristide from office in February 2004, and he fled the country into exile. MINUSTAH, which now has more than 7,000 troops and 1,700 police, was deployed later.

Neptune, in jail since June 2004, was never convicted or sentenced for any crimes before being freed Thursday. He went on several hunger strikes to protest his detention and demand his release. He was treated at a UN military hospital in March 2005.

In June, the government also ordered the release from prison of Aristide's former interior minister, Jocelerme Privert, who had been jailed for two years in the same case.