Saturday's Washington Post newspaper quotes NTSB officials as saying the report could have helped them focus on what was to become a key issue - problems with fuel tank heating - much earlier in their investigation.

A US senator responsible for airline safety told the newspaper the TWA 800 tragedy, in which all 230 people aboard perished, could have been prevented if the information had come to light earlier.

The 1980 Boeing report looked into centre fuel tank overheating problems, due to air conditioning units, in the military E-4B jet - a substantially modified version of the commercial 747 aircraft.

'Not relevant'

Complaining about a three-year delay between the crash and receiving the report from Boeing, NTSB said in a statement: "We of course were dismayed ... and we have expressed our displeasure to Boeing about their failure to inform us about the study."

However, a Boeing spokesman said the differences between the two aircraft made the report largely irrelevant to the TWA investigation.

The commercial 747 has one fewer air-conditioning units than the military jet and uses a different type of fuel.

Russ Young said: "In retrospect, although the relevance is questionable, we wish we had found it (the report) earlier and passed it along."

"We have an 83-year history of doing the things it takes to make flying safer," he said. "To suggest that we do anything counter to that is just plain wrong."

New regulations

But Senator Charles Grassley, Republican of Iowa, chairman of the subcommittee overseeing airline disaster investigations, told the Washington Post the flight 800 tragedy could have been prevented if Boeing had handed over their report when it was completed.

" If this report had been made public years ago, there would have been a lot of lives saved," said Mr Grassley.

"If the NTSB had been given the 1980 report and others, it could have pressed the FAA to set the very standards finally proposed this week for aircraft fuel tanks," he said.

On Thursday, the Federal Aviation Administration proposed regulations to make aircraft fuel tanks less susceptible to explosions.

The rules would require new planes to be fitted with fuel systems that minimise flammable vapours and force aircraft makers to develop new maintenance programs for fuel tanks within a year.

In 1990, the fuel tank of a Boeing 737, exploded near Manila airport in the Philippines, killing eight people.