WASHINGTON (AFP) - The bodies of two soldiers killed in a US Army helicopter crash have been found off the Florida coast, officials said Thursday.

The two soldiers were among 11 troops presumed to have died in Wednesday's crash of a UH-60 Black Hawk, which went down during a routine training exercise near Eglin Air Force base in Florida.

The Louisiana National Guard said it was unlikely there were any survivors from the crash.

"At this point, we're not hopeful for survivors, and we are transitioning our search and rescue to a recovery effort," Colonel Monte Cannon, vice-commander of the 96th Test Wing, said in a statement.

A civilian salvage team will need to retrieve the aircraft to allow officials to identify the remains of the victims, the National Guard said.

The Black Hawk chopper was carrying seven US Marines and a four-member air crew from the US Army national guard when it went down during a night-time training drill.

The helicopter was reported missing Tuesday around 8.30pm (8.30am on Wednesday Singapore time) near the Eglin base.

There was heavy fog in the area at the time of the accident but it was unclear if that played a role in the crash.

Search teams spotted debris from the helicopter at about 2am Wednesday and remaining wreckage was found on Thursday in the Santa Rosa Sound in Florida.

A second Black Hawk returned from the exercise safely.

The helicopters, assigned to the 1-244th Assault Helicopter Battalion in Hammond, Louisiana, were carrying out a training mission with the Marine Special Operations Regiment from Camp Lejeune, North Carolina.

The accident remains under investigation.