Undersea robots have found bodies, engines and parts of the Air France airliner that crashed into the Atlantic two years ago.
However, they have not yet found its black box flight recorders, say French officials. Investigators have said without the recorders, the reason may never be known.
All 228 people on the Airbus A330-200 were killed when the flight, en route from Rio de Janeiro to Paris, dived into the ocean on 1 June 2009, after running into an intense high-altitude thunderstorm.
The French air accident investigation agency BEA said that a team aboard the expedition ship Alucia using underwater robots had located pieces of an aircraft, and French Transport Minister Thierry Mariani confirmed that bodies had been found.
Experts from the Woods Hole Oceanographic Institute (WHOI) are leading the search under BEA authorisation. Their mission began last month and is intended to run until July.
Fifty bodies were discovered during the first phase of the search, along with more than 600 pieces of the plane scattered on the sea. No bodies or debris have been found since.
"This fourth search campaign allowed us to locate motors, landing gear, wing parts, which is a very positive sign because at last we will be able, perhaps, to find out the truth," Mr Mariani said.
The BEA said that the black boxes have not been located. "I hope to be able to announce that (discovery) in the coming weeks," a spokeswoman said, though it is far from clear whether the flight recorders would still be intact after nearly two years deep under water.
WHOI is using three Remus 6000 autonomous undersea vehicles that can operate in depths down to 6,000m for up to 20 hours at a time. Each vehicle covers an area in a 'mowing' type pattern, employing side-scan sonar to survey up to 600m to its left and right. At the end of each mission the AUV returns to the ship and its data is downloaded. If this shows evidence of any debris or other items of interest, a vehicle will be dispatched to gather more detailed, up-close images using high-resolution cameras.
Finding the cause of the crash took on new importance last month when a French judge filed preliminary manslaughter charges against Air France and the plane's manufacturer, Airbus.
Experts say without the flight data and voice recorders, authorities are unlikely to be able to determine what was at fault.
Air France and Airbus are paying for the search effort, and both organisations welcomed the latest news.
Tom Enders, Airbus president and CEO, said: "This is a relief for all those affected by this tragic event, in first place the relatives and friends of the victims. We do hope that this discovery will lead to the retrieval and the reading of the two recorders because these data are essential for the understanding of this accident."
Air France chief executive Pierre-Henri Gourgeon said: "This discovery gives hope that information on the causes of the accident, so far unresolved, will be found. Answers will perhaps therefore be found to the questions that, since 1 June 2009, families of the victims, our airline and the aviation community worldwide have asked as to how this tragic accident occurred."