The Spanish defense ministry in Madrid said that the helicopter and its crew had been returning from across the frontier.

The helicopter was travelling with another aircraft when "they lost contact with each other due to poor visibility," the ministry said.

"A search operation then began and the damaged helicopter was finally spotted on the side of a mountain which was difficult to access."

It's still not known what caused the crash.

The deaths were confirmed by crews from two US Blackhawk helicopters sent to the crash site about 50 kilometers (31 miles) east of the capital Port-au-Prince, George Ola-Davies, a spokesman for the UN Stabilization Mission in Haiti, said.

Soliders part of earthquake-relief operation

A Chilean helicopter, part of the UN peacekeeping force, had been the first to reach the scene but could not land, said Ola-Davies.

Spain's Consul General in Haiti, Juan Pedro Gomez said that the soldiers' remains "are in the process of being recovered and will be rapidly repatriated to Spain."

Spanish Defense Minister Carme Chacon was travelling to Haiti on Saturday with chief of the defense staff General Jose Julio Rodriguez to find out "first hand" the circumstances of the crash, defense ministry sources said.

The victims were part of a 450-strong military detachment aboard the supply ship Castilla, sent by Spain after the January 12 earthquake that killed 220,000 people.

rc/AFP/Reuters
Editor: Sonia Phalnikar