RIO DE JANEIRO--Red-faced Brazilian officials said late Thursday debris they thought was from an Air France crash in the Atlantic was in fact sea "trash," adding to the uncertainties surrounding the jet tragedy.

"Up to now, no material from the plane has been recovered," Brigadier Ramon Cardoso, director of Brazilian air traffic control, told reporters in the northeastern city of Recife.

Items, including a cargo pallet and two buoys, pulled from the ocean early Thursday -- which Cardoso himself had initially said came from downed Air France flight AF 477 -- actually came from another source, most certainly a ship.

"We confirm that the pallet found is not part of the debris of the plane. It's a pallet that was in the area, but considered more to be trash," he said.

The pallet was made of wood, and the Air France Airbus A330 did not have any wooden pallets on board. "That's how we can confirm that the pallet isn't part of the remains of the aircraft," Cardoso said.

He also said a big oil slick originally thought to come from the plane probably also came from a ship passing through the zone, 1,000 kilometers (600 miles) off Brazil's northeast coast.

Despite the mistake over the debris, it appeared the Brazilian navy was in the right general area where the Air France came down.

Air force planes on Tuesday and Wednesday spotted items in the water, including a seat from a plane and a seven-meter (23-foot) chunk of what looked like fuselage, which Defense Minister Nelson Jobim said were beyond a doubt from the French jet.

Air France flight AF 477 came down early Monday as it was transporting 228 people from Rio de Janeiro to Paris.

Speculation over what caused the accident has ranged from a massive, lightning-packed storm in the area at the time, to turbulence, to pilot error or a combination of factors.

No mayday call was received from the plane, just a series of data transmissions signaling it had lost power and then had either broken up or gone into a fatal dive.

Memorial services were held Wednesday in Paris and Thursday in Rio for those on board the plane, though no bodies have been spotted at sea.

Many relatives of the passengers attended, but others declined, refusing to give up hope that somehow, despite the evidence, their loved ones had survived.

French Foreign Minister Bernard Kouchner said after speaking at the Rio ceremony "it will probably take some time" before the reason for the catastrophe -- the worst in Air France's history -- would be known.

The point in the Atlantic where the plane came down is "immensely deep," between 3,000 and 4,000 meters, complicating the search for the black boxes, he said.

Jobim on Wednesday called an explosion on board the downed plane "improbable" based on the presence of slicks at the crash site, inferring that the fuel would have burned away in a blast or fire.

But with the biggest of those slicks now found to be oil from a ship, that hypothesis seemed undermined.

Also, a Spanish pilot who was flying at high altitude some distance behind the doomed Air France jetliner said he saw an "intense flash of white light," according to his airline, Air Comet.

A co-pilot and passenger also saw the bright light, according to a report initially given to Spain's El Mundo newspaper and confirmed by AFP.

"Suddenly, we saw in the distance a strong and intense flash of white light, which followed a descending and vertical trajectory and which broke up in six seconds," the unidentified captain wrote.