Aviation experts fear the cause of the Air France plane crash in the Atlantic with the loss of 228 lives may never be known.

French air accident investigators will tomorrow publish the first official report into the June 1 accident involving an Airbus A330 aircraft flying from Rio de Janeiro to Paris.

But with hopes of finding the plane's "black box" flight recorders all but gone, it is unlikely that investigators will be able to pinpoint the cause of the crash.

"We are a very long way from finding out exactly what went wrong with this flight," said Kieran Daly, editor of internet news service Air Transport Intelligence.

He went on: "It may be that we'll never know what happened to this plane. Then you would have a situation where a state-of-the-art aircraft has been lost in the middle of a flight for no known reason and that's very, very worrying."

A Yemenia Yemen Airways Airbus A310 went down in the Indian Ocean yesterday on a flight from Yemen to the Comoros islands.