It is hoped the recorder, recovered on Friday, will provide clues into the cause of the crash, which killed all 229 people on board.

At a news conference in Ottawa, John Maxwell, the director of air crash investigations for the Canadian Aviation Safety Board, said that all four tracks on the tape were working properly, and that it contained a great deal of information.

John Maxwell: No information on content of the tape

But he warned that it may take weeks to identify the individuals speaking and sort through the material.

The jet's in-flight data recorder was found in the same area last weekend but officials say that electrical failure moments before the crash prevented it from recording any data for the final six minutes of the flight.

Relevant excerpts

Mr Maxwell would not confirm whether the voice recorder contained information on the crucial missing minutes.

Under Canadian law, recordings or transcripts of cockpit voice recorders do not have to be made available to the public, although Mr Maxwell said that some relevant excerpts will probably be published.

The box was recovered from waters about 60 metres deep by divers from the Canadian forces diving team and sent in a special container aboard a commercial airline to Ottawa. Investigators extracted the tape from the box, carefully cleaned and copied it.