Estelle Youssouffa, Al Jazeera's correspondent in Paris, said authorities at Charles de Gaulle had said that there was "no hope" for the airliner.
"It seems to have simply vanished from radar screen. President Sarkozy has expressed his great concern and asked his government to put all its efforts into finding the missing plane," she said.
Sarkozy told relatives waiting for their loved ones at the airport that there was a "slim" chance of anyone being found alive.
The Brazilian air force, which sent aircraft from the island of Fernando de Noronha,
off the country's northeast coast, to look for the Air France jet, said it was far out over the the sea when it went missing.
Al Jazeera's Gabriel Elizondo, reporting from Sao Paulo, said Fernando de Noronha is very close to where authorities last had radio contact with the airliner.
"There's definitely an urgency here and the Brazilian head of the military has sent out a statement saying he's going to be working very closely with the French authorities to scramble any resources necessary until this plane is found," he said.
France sent an aircraft from Senegal and asked Washington to use its spy satellites and listening posts to help with the search.
Officials said that the search was centred on an area more than 1,100km off the Brazilian coast.
"This zone is on the line between the jurisdiction of Brazilian air control and that of Dakar in Senegal," a Brazilian air force spokesman said.
Jean-Louis Borloo, the French environment minister, said there were "powerful" tropical storms in the area where the airliner dropped off the radar.
"It is the kind of jet made to handle this kind of circumstance but there must have been a build-up of circumstances," he said.
Barry Gromett, a meteorologist at the London Weather Centre, said that the aircraft was passing through an area known as the Intertropical Convergence Zone.
|The Airbus A330 has a good track record, with only one other crash on record [AFP]
"It is a zone in the tropics where you can have particularly deep thunder clouds," he said.
Jim Morris, an aviation expert and former pilot for the the UK's Royal Air Force, told Al Jazeera that while modern aircraft are "designed to withstand a lightning strike", an electrical storm could still cause damage.
"It can cause structural damage such as burning through and blowing out rivets and it can potentially cause electro-magnetic interference with the flight control systems," he said.
In a statement, Airbus said the missing airliner had been delivered to Air France from the production line in April 2005.
The company said the the aircraft, which was powered by CF6-80E1 engines, had accumulated approximately 18,800 flight hours in some 2,500 flights.
The Airbus A330 family of aircraft has a good safety record.
Its first, and last crash, was on June 30, 1994, when an A330 crashed on a test flight shortly after takeoff from Toulouse in France, killing all seven on board.