Paris - The investigation of the Air France crash that killed 228 people is in "a race against time," a French investigator said Wednesday in Paris.

The area in the Atlantic Ocean being searched for victims, the plane and its two black boxes is "a very difficult environment," with a maximum depth of 4,600 meters, said Olivier Ferrante, of the Bureau of Accident Inquiry and Analysis (BEA).

In addition, "the area is little known," he noted, while the signal the black boxes emit has a range of only 2 kilometers and is guaranteed for only 30 days.

That leaves the ships and planes currently combing an area of about 17,000 square kilometers only two weeks before chances of finding the black boxes are reduced to virtually nil.

The black boxes - a cockpit voice recorder and a flight data recorder - are considered essential in discovering the reason the Airbus A330-200 plane carrying 216 passengers and a crew of 12 plunged into the Atlantic on June 1 on a flight from Rio de Janeiro to Paris.

BEA head Paul-Louis Arslanian told journalists in the French capital that investigators had "no special new elements" to explain the accident.

In addition to the 50 victims taken out of the waters, about 400 pieces of the plane have been recovered, he said.

Autopsies have been carried out on some of the recovered bodies by Brazilian forensics experts, but French investigators have not yet been given access to the results, Arslanian said.

"We consider the results important for the investigation. We need to know the results," he said.

But he said the key to the investigation remained the black boxes.

"We are certain that the recorders will signal for at least 30 days. For us, this is the only thing we have to go on. Afterwards, it becomes uncertain," Arslanian said. (dpa)