Silverstone: McLaren team principal Martin Whitmarsh hit out on Friday at a Formula One rule change that looks certain to give championship rivals Red Bull a clear boost on the track.
Red Bull, who already lead the drivers' and constructors' championships are to benefit from a concession under new technical rules introduced this weekend.
The change concerns the amount of exhaust flow allowed from Red Bull's Renault engines that, supposedly, were introduced to ban a so-called 'blown diffusers' system previously in use.
The changes came into the open during Friday's practice sessions and led to a row between Whitmarsh and Red Bull principal Christian Horner.
"When the goalposts are moving part-way through a practice session, then I think it makes it quite difficult," said Whitmarsh.
"I think that with the benefit of hindsight, it would have been better to make changes at year end - which I think Christian would agree with."
Following prolonged discussions involving Red Bull's engine suppliers Renault and the FIA, the sport's governing body, the champions are now allowed to keep using 50 percent of their exhaust flow, when the driver is off-throttle, for reliability reasons.
Originally they were to have none at all, then 10 percent and most recently 20 percent - until last-gasp talks rescued half the original flow for the team on Friday morning.
"I think that to do this and to do it in a fairly cloudy and ambiguous, and changing way - well, inevitably, in a competitive environment, every team feels that it's been hard done by," said Whitmarsh.
"At the moment, I think potentially a lot of teams will end up making an argument to 'cold blow'.
"Renault have been in that domain for some time, other teams haven't and don't have that experience but we're talking about a very substantial performance benefit here..."
"And the fact that these things were only coming out during the course of today is extraordinary."
Horner hit back claiming that McLaren, powered by Mercedes-Benz engines, had been given a dispensation to use a "fired over-run" that was unfair to Red Bull.
"I think it would be unfair to allow fire over-run and not allow the same parameters for another engine manufacturer," he added.
"I think it's a very, very difficult job for the FIA to pick their way through this and I think all credit to them. They've looked to try and be as fair, balanced and equitable as they decreed.
"I'm sure there are a lot of conspiracies in the paddock that these are the reasons why Red Bull is performing - or McLaren is performing - or some cars aren't performing."
"So, if you can do it, then you're going to try and do it aren't you?"
Even without the added concession Red Bull's Mark Webber was quickest in Friday's free practice ahead of Sunday's British Grand Prix.