US government investigators in December issued a report that said investigations ''strongly supported'' that pilot suicide could have caused the Boeing 737 to crash in Indonesia in 1997 and kill all 104 people on board.

Indonesian investigators concluded at the same time that there was not enough evidence to say what caused the crash.

The International Federation of Air Line Pilots' Associations said in a statement received on Friday that the US National Transportation Safety Board, or NTSB, report was not thorough.

''The NTSB, finding no convenient ''smoking gun'' and relying on a psychological autopsy, concludes that the Captain of the flight committed suicide and was responsible for the murder of his passengers and crew,'' the statement said.

''There were no recordings of the final minutes of the flight. The high speed of the impact in a difficult location resulted in little surviving physical evidence.''

The London-based pilots' body, which represents about 100,000 pilots worldwide, said the fact that the US ''feels the need to contradict the conclusions of an international investigation based upon simple conjecture is inexcusable''.

The NTSB contributed to the final report on the crash investigation because the plane that crashed was made by American company Boeing. The investigation was led by Indonesia, and Singapore investigators also took part.

The nearly-new Boeing 737-300 plunged into a river on Indonesia's island of Sumatra on December 19, 1997, while en route from Jakarta to Singapore. The plane belonged to SilkAir, a subsidiary of flag-carrier Singapore Airlines.

''Suicide committed by pilots of commercial aircraft is an event so rare that it has never been positively documented by any investigation,'' the statement said. ''Now, in the space of two years, the NTSB has inferred the existence of a suicide in two separate accidents. In neither case can the allegation be proven.''

The US body also suggested suicide was to blame for a 1999 EgyptAir crash, saying the co-pilot may have intentionally plunged the airliner into the Atlantic Ocean off the Massachusetts coast on October 31, 1999.

EgyptAir rejected the findings.