The first electronic clues as to what caused an Airbus A330 jet to disappear over the Atlantic emerged Friday, though it is still unknown where and why the plane went down.

Investigators believe the crash may be the result of technical malfunction, but the French Office of Accident Investigations and Analyses (BEA) issued a statement against making "any hasty interpretation or speculation on the basis of partial or unconfirmed information."

No pieces of wreckage from the missing plane have been uncovered. Brazilian authorities announced they had discovered debris relating to the crash off its northeastern coast, but six hours later retracted their statement. An oil slick in the sea, also thought to be from the Airbus A330, was later found to be from an oil ship.

The only clue so far comes from the automatic messages sent out by the aircraft just before it hit a thunderstorm on June 1, 2009.

According to the French air safety investigation agency, "based on the analysis of the automatic messages broadcast by the plane, there are inconsistencies between the various speeds measured."

Investigators therefore do not know if the AF 447 was traveling at the wrong speed as it cut through the storm. According to an unnamed aviation expert, air speed sensors operate on air pressure and may give inaccurate readings if they are obstructed by objects such as ice. If the pilots think the readings are correct, they may adjust their speed at the wrong times, putting the plane in danger.

All 228 people on board Air France flight 447 from Rio de Janeiro to Paris died in the crash.

Search continues

A frantic search for wreckage is still underway by Brazilian navy vessels, and French and Brazilian planes.

"Time is against us," said French transport minister Dominique Busserau. "We must do everything we can to find the flight recorders and certainly enlarge the search zone."

Several debris sites covering a 90 km (56 miles) area are being investigated by crash searchers and boats.

Meanwhile, Airbus issued a warning to airline crews to follow standard procedures if they think their speed indicators are faulty. They also stated that this does not imply that the pilots were at fault or that there was a problem in the design of the Airbus A330 jet.

An industry official said warnings are only sent out if the facts determined from an accident investigation are important enough to relay immediately to the airlines.

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Editor: Trinity Hartman