Anger over rule changes

SILVERSTONE, ENGLAND // The heat is on and the gloves are off. Formula One's decision to prohibit off-throttle exhaust-blown diffusers ended in a fiery exchange of words during yesterday's post-practice press conference ahead of tomorrow's British Grand Prix.

Martin Whitmarsh, the team principal of McLaren-Mercedes, is concerned rivals Red Bull Racing are benefitting from the latest mid-season rule change and he let his feelings be known during a public argument with Red Bull counterpart Christian Horner.

After a regulation tweak remarkably took place midway through yesterday morning's practice session, Whitmarsh called the decision by the world motor sports governing body "cloudy, ambiguous and changing". Horner instead said he viewed it as "fair, balanced and equitable".

"The rules are slightly fluid and appear to change by the hour at the moment," Whitmarsh said. "We were a little surprised when the regulations changed halfway through FP1, and I'm sure that has put many teams on the backfoot. It makes it very difficult. Every team feels hard done by."

Horner commended the FIA for acting in a "fair and proper manner" before adding "a lot of focus has been placed on us and whether we have a silver bullet in our car. We don't."

Mark Webber, the Red Bull driver, set the fastest time in wet practice yesterday, topping the times in the first session. Felipe Massa's Ferrari was quickest in the second session.