PARIS - The Air France jet that crashed into the Atlantic Ocean on Monday was flying too slowly ahead of the disaster, Le Monde newspaper said on Thursday, citing sources close to the inquiry.

The paper said the manufacturer of the doomed plane, Airbus, was set to issue a recommendation advising companies using the A330 aircraft of optimal speeds during poor weather conditions.

Airbus declined to comment on the report and the French air accident investigation agency, which has to validate any such recommendations, known as an Aircraft Information Telex, was not immediately available for comment.

The Air France A330-200 was en route from Rio de Janeiro to Paris when it plunged into the Atlantic four hours into its flight. All 228 people on board died.

The plane sent no mayday signals before crashing, only a stream of automatic messages over a three minute period after it entered a zone of stormy weather, showing a rapid succession of electrical faults followed by a loss of cabin pressure.

It was not clear if slow air speed alone could trigger such a cataclysmic breakdown of aircraft systems, but any recommendations from Airbus about its A330s would fuel speculation over the causes of the crash.

FLASH OF WHITE LIGHT

Experts have questioned whether extreme turbulence or decompression during stormy weather might have caused the disaster -- the worst in Air France's 75-year history.

Spanish newspaper El Mundo said a transatlantic airline pilot reported seeing a bright flash of white light at the same time the Air France flight disappeared.

Suddenly we saw in the distance a strong, intense flash of white light that took a downward, vertical trajectory and disappeared in six seconds, the pilot of an Air Comet flight from Lima to Madrid told his company, the newspaper reported.

A spokesman for Madrid-based airline Air Comet was not immediately available to confirm the El Mundo article.

Asked about whether there could have been an explosion or bomb on the plane, an armed forces spokesman in Paris said they were not ruling anything out at the moment.

Everyone has doubts about everything at the moment and we do not have the slightest beginnings of an answer yet, said armed forces spokesman Christophe Prazuck.

Search crews flying over the Atlantic have found debris from the jet spread over more than 55 miles of ocean, about 685 miles northeast of Brazil's coast.

Prazuck said the priority was to localize debris and retrieve it as soon as possible before it sank. He added that sea currents were dispersing the wreckage.

Brazilian naval vessels are heading to the crash zone and a French frigate is due to arrive in the area on June 7. A boat carrying a mini submarine capable of hunting the plane's black boxes is expected to arrive there on June 12.

One French and two Dutch cargo ships that are nearby the crash site have been asked to help find debris, Prazuck said.

(Reporting by Crispian Balmer and Estelle Shirbon in Paris and Andrew Hay in Madrid; Editing by Alison Williams)