A body from the 2009 Air France crash that killed all 228 people aboard has been raised from the depths of the Atlantic Ocean, after being found still attached to the plane seat and in the vicinity of several others.

Recovering the remains Thursday morning involved great technical difficulty, and it was unclear if all bodies found in the latest search could be recovered, the Associated Press reports.

The body was preserved by high pressure and low temperatures as it lay in crash wreckage, 3,900 meters (12,795 feet) deep on the sea floor. It was brought it aboard their search vessel off Brazil's northeast coast from a robot submarine.

Fifty bodies were found floating in the ocean during the first search effort immediately after the crash.

The raising of the body comes two days after the Airbus A330's cockpit voice recorder was pulled from the ocean, while the data memory unit had been found days earlier. 

It is hoped the two black boxes will reveal why AF447 from Rio de Janeiro to Paris crashed into the Atlantic. The European aircraft manufacturer and the airline are being investigated for involuntary manslaughter. The crash has been partly blamed on malfunctioning speed sensors used by Airbus.

A spokesman for France's national police in Paris said recovery workers had been working since Wednesday to bring the body to the surface.

"It's difficult because the bodies are well preserved on the seabed with the pressure and the temperature, but bringing them up through warmer water causes decomposition," he said, Al Jazeera reports.

Investigators on board the search vessel had taken DNA samples from the body, the French Interior Ministry reportedly said. 

Relatives for the victims have demanded that all the bodies be recovered from the wreck, but the police warned that the deep-water operation faces "highly complex and unprecedented conditions," Al Jazeera writes.

Alan Bouillard, the official of France's Bureau of Investigation and Analysis (BEA) in charge of the probe, has said the team faced "a real challenge."