SAO PAULO, BRAZIL – The mystery of what happened to Air France flight 447 continues. The Brazilian Air Force said none of the debris they had recovered from the Atlantic Ocean on Thursday belonged to the missing Airbus.

Officials said a cargo pallet recovered by helicopters was not from the missing plane.

In addition, the "jet fuel" slicks spotted in the area were not jet fuel, but likely oil from a passing ship, Air Space Control Department Brig. Gen. Ramon Borges Cardoso told reporters Thursday.

“We have not recovered any parts of the aircraft so far,” General Borges Cardoso was reported as saying. "The oil that we found today was not airplane fuel; it was from a ship. It was oil, not kerosene."

A Brazilian Air Force official confirmed Cardoso’s statement and said a detailed communiqué would be released later.

The Brazilian military has spotted other debris from the air, including what appears to be a 23-foot (seven-meter) chunk of metal, an airline seat, and several large brown and yellow pieces that Cardoso said probably came from inside the plane.

But there's been no confirmation yet that any of that debris spotted 340 miles (550 kilometers) northeast of Brazil’s northern Fernando de Noronha islands has been recovered or identified as from the Air France flight 447, which disappeared on Sunday night with 228 passengers aboard.

Until now, Brazilian officials say, the focus was on finding survivors. But none have been spotted, and the military will now start picking up debris in an attempt to identify the plane, they say.