Investigators believe tyre damage started deadly chain of events

Investigators believe shreds of the split tyre could have pierced a fuel tank on the aircraft or damaged one of its engines.

The 40cm (16 inch) metal strip fitted the shape of a cut in one of the tyres, the BEA said.

It said the plane was travelling at 315km an hour (195mph) when the tyre burst.

'Rapidly damaged'

"According to a process which has yet to be determined, one or several fuel tanks on the left wing were very rapidly damaged, causing a major fuel leak and the fire," the statement said.

It was the first time the BEA had given a clear idea what caused Flight AF4590 to plough into a hotel in the town of Gonesse just minutes after taking off for New York.

All 109 passengers were killed, as well as four people on the ground.

Investigators have resumed their search

It was not yet clear where the metal strip had come from, the investigators said.

Captain Xavier Mulot, heading the inquiry by France's air transport police, told a press conference that about 20 objects had been found on and around the runway following the accident.

"I cannot say today if the metal strip found on the runway was part of the Concorde or not," he said, although the BEA said last week the metal strip did not come from the crashed plane.

Debris

He said that between 500 and 1,000 pieces of evidence were being examined in the inquiry.

On Thursday investigators resumed gathering debris from the crash site. The work had been temporarily halted a week ago after cancer-causing asbestos from the doomed aircraft was found in the engines.

Meanwhile, a report in UK-based publication New Scientist has questioned the safety of Concorde's engines. The report says a 1998 study commissioned by British Airways shows 55 "significant risks" inherent in the engine design.