In this photo released by the French military Wednesday, soldiers approach a piece of debris believed to be part of Air France Flight 447, during continuing searches for bodies and pieces of the plane. (ECPAD/Associated Press)

Autopsies on some victims of the Air France Flight 447 disaster show the bodies have multiple fractures but are not severely fragmented, suggesting the plane broke up in the air, a report said Wednesday.

A spokesman for Brazilian medical examiners carrying out autopsies on the 50 bodies that have been recovered told The Associated Press they had multiple fractures of legs, hips and arms. The official spoke on condition he not be named due to department rules.

A former U.S. National Transportation Safety Board official said those injuries could mean the plane broke apart in the air. Frank Ciacco said bodies would be severely fragmented if the jetliner hit the water intact.

A Brazilian navy diver checks a piece of debris from Air France Flight 447 in the Atlantic Ocean, about 640 kilometres northeast of Brazil's outlying islands. (Brazilian navy/Reuters)

Earlier Wednesday, French investigators said they had found more than 400 pieces of the plane that crashed into the Atlantic Ocean off the coast of Brazil on May 31. The Airbus 330 was en route from Rio de Janeiro to Paris with 216 passengers and 12 crew on board when it disappeared from radar screens as it flew through stormy weather. All are believed dead.

Speaking at a news conference near Paris, French air accident investigation agency head Paul-Louis Arslanian said the debris is from all areas of the plane. He didn't provide any further details about the recovered wreckage or say how much of the entire plane has been found.

The search for the aircraft's voice and data recorders is intensifying, Arslanian said.

"We are at the first days of the research underwater, research which is focused on the time being on the recorders and more precisely the beacon, the acoustic beacon which is fitted to the recorders," he said.

Investigators are using manned and unmanned submarines to search the crash site, which is spread over more than 230 kilometres, located about 640 kilometres northeast of Brazil's Fernando de Noronha islands.

The ocean floor where the debris has been spotted is as much as 7,000 metres deep.

It's still too early to draw any conclusions on why the jet went down, Arslanian said.

"It is premature for the time being to say what happened and it would be irrelevant and misleading to elaborate on partial and from time to time erroneous facts," he said.

Drawing on his lengthy experience as an air crash expert, Arslanian said crash investigators are working in "one of the worst contexts for an aviation investigation."

With files from The Associated Press