UPDATE 11-Air France jet missing over Atlantic with 228 aboard

* No sign of jet with 228 people on board

* Sarkozy says chances of finding survivors "tiny"

* Brazilian, French planes, ships search for wreckage (Recasts, adds possible debris, Vale passenger, paras 6, 20)

By Estelle Shirbon and Stuart Grudgings

PARIS/RIO DE JANEIRO, June 1 (Reuters) - An Air France jet disappeared after hitting stormy weather over the Atlantic Ocean on Monday and all 228 people on board were feared dead.

France and Brazil sent military planes and ships to scour a vast area of ocean where the Airbus A330 jet may have come down during the flight from Rio de Janeiro to Paris. But officials said there was little chance that anyone could have survived.

"It's a tragic accident. The chances of finding survivors are tiny," French President Nicolas Sarkozy said at Paris's Charles de Gaulle airport after meeting passengers' relatives.

If no survivors are found, it would be the worst loss of life involving an Air France plane in the carrier's 75-year history. An Airbus A330 has never been lost during a commercial airline flight and it is extremely unusual for an airliner to be brought down by storms.

The plane was carrying 216 passengers of 32 nationalities, including seven children and one baby, Air France said. Sixty-one were French citizens, 58 Brazilian and 26 German. Twelve crew members were also on board. [ID:nL1193930]

Brazil's air force said it was investigating a report that a jetliner flown by Brazilian carrier TAM had spotted debris in the ocean in Senegal's air space on a flight from Europe to Brazil. Brazil's Vice-President Jose Alencar also mentioned the report, saying the TAM pilot may have seen "something on fire" in the ocean. TAM was not immediately available for comment.

The Air France jet flew into storms and heavy turbulence four hours after take-off from Rio and 15 minutes later sent an automatic message reporting electrical faults, the airline said.

There was no sign that the crew had sent a mayday message or any indication that signal-emitting emergency locaters had activated on impact as is normally the case in crashes.

The company said a lightning strike could be to blame and that several of the mechanisms on the Airbus 330-200 (EAD.PA), which has a good safety record, had malfunctioned.

"It's too early to tell what went on and what caused this tragedy," Isabelle Birem, Air France's general director in Brazil, said at a news conference in Sao Paulo.

"We need to study the technical results from the black box," she added, referring to the cockpit recorder.

Sources with access to flight data sent to the World Meteorological Organization said two Lufthansa jets passed through the same area of turbulence on Monday without incident. Aviation experts said lightning strikes on planes were common and could not alone explain a disaster. [ID:nL1719357]