SILVERSTONE (England) - RED Bull dominated practice on Friday for Formula One's British Grand Prix with Sebastian Vettel and Mark Webber fastest in both sessions.

Vettel set a fastest lap of 1 minute, 19.4 seconds late in the first session on a day when action on the track was overshadowed by the announcement that eight of Formula One's 10 teams, including Red Bull, will form a rival series after failing to resolve their dispute with the FIA, the sport's governing body.

The FIA retaliated by suing the Formula One Teams Association.

Vettel was 0.056 seconds slower in the second 90-minute session, when Webber reduced the gap on his 21-year-old German teammate to 0.197.

Championship leader Jenson Button had a disappointing day on the Silverstone track, completing a lap of his home circuit in 1:20.227 in the morning but slumping to 14th later in the day.

Button has won six of the season's first seven races to lead the overall standings by 27 points from teammate Rubens Barrichello, who was fourth in the morning, dropping two places in the afternoon.

Brawn GP chief executive Ross Brawn said he expects a difficult race from the Red Bulls.

'They're too quick,' he said. 'I think we're going to have trouble this weekend.' Force India's Adrian Sutil was the third fastest driver overall after posting a time of 1:20.141 in the second session.

Lewis Hamilton, who won the race last year by 68 seconds, was seventh in the second session in his McLaren. -- AP