A French news report says the Air France jetliner that crashed into the Atlantic Ocean Monday may have been flying too slowly to navigate the fierce tropical storms that apparently downed the plane.

All 228 people aboard Flight 447 are presumed dead. The plane was flying from Rio de Janeiro to Paris when it crashed off the northeast coast of Brazil.

The Paris newspaper Le Monde said Thursday that Airbus, the manufacturer of the doomed plane, was preparing to send a warning to operators of hundreds of its A330 jets with new advice on flying in storms.

Airbus has refused comment on the report, which cites a source close to the crash inquiry.

In Rio de Janeiro Thursday, the foreign ministers of France and Brazil joined dozens of mourning relatives of the passengers and crew at a memorial service.

Meanwhile, Brazilian naval ships have begun collecting wreckage from Flight 447.

The ships failed in heavy seas Wednesday to find any trace of survivors and are now turning their attention to salvage efforts as seas calmed Thursday. French ships, including one carrying two unmanned submarines, are due in the area early next week.

The submersibles are widely seen as the best hope for retrieving Flight 447's all important flight recorders, which are believed to be sitting on the ocean floor at depths of at least 3,000 meters. If found intact, the recorders could help explain how the giant aircraft fell out of the sky from an altitude of about 9,000 meters without any distress calls from pilots.

Officials have said they see no signs of terrorism in the crash. But chief French investigator Paul-Louis Arslanian says the exact cause of the disaster may never be known.

Some information for this report was provided by AFP, AP and Reuters.