Concorde has experienced "potentially catastrophic" problems with tyres prior to Tuesday's fatal crash, according to US safety officials.

In Washington, the National Transportation Safety Board (NTSB) has released details of four incidents in which Air France Concordes blew tyres on take-off.

Concorde tyres are one focus of the investigation

The incidents took place at American airports between 1979 and 1981.

In a letter to the French aviation authorities sent in 1981, the NTSB said that in June 1979 an Air France Concorde experienced blow-outs of tyres numbers five and six on the left-hand side while taking off from Washington's Dulles Airport.

Tyre debris and wheel shrapnel, it said, resulted in damage to number two engine, the puncture of three fuel tanks and the severance of several hydraulic and electrical wires.

A large hole was also torn in the skin of the top wing.

There was a similar incident a month later. In all, the letter says, there were four such occasions in which an Air France Concorde was involved in a potentially catastrophic incident resulting from blown tyres during take-off.

Criticisms

The letter recommended that each tyre and wheel be inspected before take-off, and that if a problem was suspected during take-off, the landing gear should not be retracted.

It further said that an emergency landing should be made if the condition was doubtful.

The letter criticised crews who on two subsequent occasions experienced blow-outs but raised the landing gear nevertheless.

One plane flew on to Paris, but the other had to land in New York because there was damage to an engine.

In a letter of reply also released by the NTSB, the chief French accident investigator said that it was already Air France procedure not to raise the landing gear, and in such a case, an immediate landing must take place.