BA says it has written to the Unite union on Tuesday, outlining "irregularities" in its ballot of workers, which it says makes the vote invalid.
The airline says it is now seeking a court injunction to stop the strike after the union ignored a 2 p.m. deadline - in local time - to call off the walkout.
The planned strike follows a dispute with cabin crew over job losses and changes to work practices.
BA has said the series of sweeping changes are necessary to cut costs after the airline was hit by a downturn in passenger demand thanks to the global economic crisis.
