US airlines must now replace speed probes built by France's Thales SA on some of their Airbus planes, amid fears the instruments contributed to the crash of an Air France jet in June.

The US Federal Aviation Administration's (FAA) order, which affects Airbus A330 and A340 jets, was published Wednesday in the Federal Register and takes effect on September 8.

The FAA has given US carriers until January to replace the sensors, also known as "pitots," with new ones built by the US firm Goodrich Corp.

Airbus and the European Aviation Safety Agency (EASA) issued a similar recommendation on July 31.

"We have reviewed the numerous airspeed anomalies recently reported and we have determined that an unsafe condition exists," read the FAA decision.

The order affects some 40 Airbus A330s ? and no A340s ? operated by US carriers US Airways and Delta Air Lines, FAA spokesperson Laura Brown told AFP.

Investigators believe false data from speed monitors could have contributed to the June 1 crash of Flight 447 in the Atlantic that killed all 228 people on board, the worst disaster in Air France's 75-year history.

The French accident investigation agency BEA confirmed that the older version of the Thales speed monitors gave false airspeed data to the cockpit of the flight from Rio to Paris before it plunged into the ocean.

The BEA has said the faulty sensors were a contributing factor but not the cause of the crash, which has yet to be explained.