Search teams flying over the Atlantic have found debris from a crashed Air France jet spread over more than 55 miles, officials said.
The size of the area involved reinforces the possibility that the plane broke up in the air.
Newly-spotted traces of the plane included a 12-mile oil slick and a metal object 23ft in diameter.
Brazilian Defence Minister Nelson Jobim said the existence of the fuel stains in the water ruled out an explosion, undercutting speculation about a bomb attack.
"The existence of oil stains could exclude the possibility of a fire or explosion," he said. "If we have oil stains, it means it wasn't burned."
Experts said extreme turbulence or decompression during stormy weather may have caused the Airbus A330, which took off from Rio de Janeiro bound for Paris on Sunday night, to disintegrate over the ocean with 228 people on board.
Two Brazilian navy ships have arrived in the crash area, about 685 miles northeast of Brazil's coast, but have yet to retrieve any debris.
French officials said they may never discover why the plane went down as the flight data and voice recorders may be lost at the bottom of the ocean.
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