The United States will offer all help necessary to France in its investigations into what caused the disappearance of an Air France flight with 228 people on board, U.S. President Barack Obama told the local media on Tuesday.

In an interview with i-TV, Obama said he could not comment in detail because it was unclear what had happened to the plane.

The Pentagon said on Monday it had sent a surveillance aircraft and an Air Force search and rescue team to help locate the plane.

Meanwhile, French and Brazilian rescuers continued to work overnight.

Colonel Jorge Amaral, Brazil's air force spokesman told the media a Hercules C130 plane fitted with equipment that can detect the Air France plane's emergency beacon, and an Embraer R-99 aircraft with infrared equipment that could detect bodies in the water, have been used in the search operation.

French President Nicolas Sarkozy on Monday said at Paris Charles de Gaulle airport that the cause of the plane's disappearance remains unclear and "no hypothesis" is being excluded.

Defense Minister Herve Morin said there were no signs so far indicating terrorism was involved.

A Pentagon official, who spoke on condition of anonymity, also said he had seen no indication of terrorism or foul play.

Air France said on Monday that the jet was probably hit by lightning and suffered an electrical failure while flying through an Atlantic storm.

But experts do not believe that a simple bolt of lightning could have caused the loss of the airplane.

"There really had to be a succession of extraordinary events to be able to explain this situation," the French government minister overseeing transportation, Jean-Louis Borloo, told a radio station on Tuesday.

The Air France plane went missing over the Atlantic off the Brazilian coast. Flight 447, an Airbus 330-200 bound for Charles de Gaulle airport in Paris, lost contact with the control center shortly after takeoff from Rio de Janeiro on Sunday at 7 p.m. (2200 GMT). It was expected in Paris on Monday at 11:15 a.m. (0915 GMT).

The flight was carrying 216 passengers and 12 crew members. The passengers included one infant, seven children, 82 women and 126 men, according to Air France. Nine Chinese nationals were on board the plane.

(Xinhua News Agency June 2, 2009)