PORT-AU-PRINCE (Reuters) - Searchers may never recover the bodies of dozens of people killed when an overcrowded Haitian bus was swept away by floodwaters triggered by Tropical Storm Fay, officials said on Tuesday.

As many as 50 passengers were missing after the bus tried to cross the rain-swollen Riviere Glace in the southwestern province of Grand-Anse on Sunday. Some 27 people survived the accident and three bodies, those of two men and a child, have been recovered, officials said.

"The survivors explained to us that passengers were squeezed together on the bus," said Oreste Andre, mayor of the town of Bomont, where the incident occurred. "We have no doubt over 50 people died in this catastrophe."

Fay killed at least seven others in Haiti, the poorest country in the Americas, as well as one in the Dominican Republic and two in Jamaica before reaching the United States, where it swept across Florida on Tuesday.

Marc Daniel Andre, the local coordinator for the Red Cross in the Grand-Anse area, said survivors told rescuers that 50 of the 75 or 80 people on the bus were missing.

"We will never be able to find all those people," he said. "Before the water gets to where we could reach them, it passes through a place called Trou Canari where bodies could be stuck."

Maxime Roumer, a former senator from the area, said it would be dangerous to send searchers to recover bodies in Trou Canari, a virtually inaccessible area of steep cliffs and ravines.

"Those who know the area know about Trou Canari. If you fall there, there is no way to go and get you. You are simply lost forever," Roumer said. "Nobody will want to go to those places to search for bodies."

Thema Laurent, who witnessed the accident and helped rescue some of the survivors, said he saw many passengers taken away by the river.

"Some were trying to call for help but we could not do anything for them. Those who were saved had a chance to get out through an open back door that was not under water, and got on top of the bus."

The bus, en route from the capital, Port-au-Prince, to Jeremie, the largest city in Grand-Anse, was overcrowded because it had picked up passengers who had intended to travel by boat but were stranded at the wharf by Tropical Storm Fay.

"No one wanted to be left behind. Everyone wanted to get on board," Oreste Andre said.

(Editing by Jim Loney and Cynthia Osterman)