Silverstone: Qualifying for the British Grand Prix was overshadowed on Saturday by a row after Formula One's ruling body the FIA performed a u-turn on its technical rules on the eve of Sunday's race.

As defending champion Sebastian Vettel clocked the fastest time in the morning's final free practice all eyes were focussed on the stewards' room where Red Bull team chief Christian Horner stormed in to protest.

"I am going down to speak to Charlie (Whiting, the FIA race director) about it," said a testy Horner as he marched through the paddock.

"I am not saying anything else.." It was the same story as he left following an exchange of views. "No comment at this time," he snapped.

This pantomime scene followed Friday' act of public bickering between Horner and his McLaren counterpart Martin Whitmarsh over the FIA's decision, taken during Friday's practice action, to allow Red Bull a special concession in the latest tightening up of the regulations.

Team Lotus boss Tony Fernandes described the series of events as "a shambles.

The row centred on the new rules that ban the deliberate use of engine exhaust gases to improve rear down-force, and therefore grip, notably when the driver is not pressing down on his car's throttle - a practice that, it was believed, contributed towards Red Bull's clear performance advantage this year.

Initially, the FIA banned all use of 'blown' exhaust fumes in this way, but this provoked a storm of protest.

The FIA relented, allowing teams running with Mercedes engines - including McLaren - to let their engines over-run under braking, thus creating some 'blown exhaust' even when the driver was off the throttle.

This concession to McLaren left Red Bull fuming and led to their own pleas for equality, based on a need for 50 per cent throttle usage under braking for teams with Renault engines.

This concession, on Friday, sparked the public row between McLaren and Red Bull and was followed, on Saturday morning, by the FIA's decision to withdraw the concession given to the Renault-powered teams on Friday.

The overnight u-turn was widely regarded as a victory for the Mercedes' teams, but many fans, large sections of the media and further numbers of seasoned paddock observers were left bewildered.

The Red Bull team garage was immediately in uproar.

Horner, visibly angry, and technical chief Adrian Newey, together with a Renault engineer marched through the paddock to see the stewards 'for clarification', F1-speak for an unofficial protest and further rumpus.

Later, after a meeting between the teams Horner said he was not intending to lobby for any further changes - and was accepting what they perceived as a serious disadvantage for this weekend.

"We need all the teams to agree on this and to move on and put it behind us," said Horner.

"At the moment, in our opinion, we are running at a disadvantage compared to other manufacturers. We're trying to find a solution. The simplest thing would be to go back to the way we were two weeks ago.."

Few other teams have said they agree with Horner, but he added that the FIA had said it was prepared to make further concessions and reach a compromise deal during the next two weeks.

Ferrari were notably silent on the row, but they are one of the few teams on the grid not using the so-called 'blown diffuser' system.