NEW YORK (AP) _ British Airways plans to start offering smoke-free international flights between London and San Francisco and Los Angeles, becoming the biggest trans- Atlantic carrier to offer the lure to non-smokers.

British Airways, which runs two flights per day from each of the California cities to London, will make the first flight from each city smoke free.

John Lample, a spokesman for the airline, said parts of the plans have yet to be finalized and the program is to be announced officially on Tuesday. The smoke-free option is to be offered on a trial basis on the half-day flights beginning Sept. 1 and is expected to last for a few months.

Smoking is barred on U.S. domestic flights and flights between the United States and Canada.

Virgin Atlantic Airways offered non-smoking flights between New York and London in the summer of 1990, shortly after smoking was banned on domestic U.S. flights. The airline dropped the restriction after British passengers objected, said Lori Levin, Virgin spokeswoman.

Sandy Gardiner, another British Airways spokesman, said the experiment wouldn't start until September because many passengers have already booked flights for the summer expecting to be able to smoke.

Other major U.S. airlines said there were no immediate plans to ban smoking on trans-Atlantic flights.