Mercedes and Pirelli face punishment from the FIA after conducting an unauthorised tyre testing session after the Spanish Grand Prix two weeks ago.
Almost five hours after the conclusion of Sunday's Monaco Grand Prix, the FIA said that a tribunal "may decide to inflict penalties".
Mercedes, who won their first F1 race for over a year and only the second in their recent evolution, could face a points deduction, a race ban or a fine. The result is likely to stand. Pirelli, who could face a hefty fine, are still waiting to be confirmed as next year's tyre suppliers.
Even before the German's win Red Bull and Ferrari had filed complaints concerning Mercedes' alleged illegal testing of Pirelli's controversial tyres following the previous race in Barcelona. And Mercedes had no time to reacquaint themselves with the taste of squirted champagne before the row had deepened further.
Helmut Marko, Red Bull's special consultant, claimed Mercedes could have gained a one second per lap advantage by testing for three days between the two races. He said: "We are very unhappy. When we test for three days, we go a second faster – that's what Adrian Newey [Red Bull's designer] says. It definitely helped them – you can see that they had no tyre problems today. That's no accident."
Even as he spoke, Pirelli and the FIA, the sport's governing body, were locked in discussions in an attempt to unravel the situation. Marko said: "There are sporting regulations that cannot be overridden by a civil agreement between Pirelli and the FIA. The sporting regulations state clearly when and how you can test. We are seeking clarification of how to proceed and that the competitive advantage of Mercedes is compensated in some way".
FIA said on Sunday night that it had not been kept up to date with plans for the test following Pirelli's approach. "At the beginning of May, the FIA was asked by Pirelli if it was possible for it to carry out some tyre development testing with a team, using a current car," a FIA statement read.
"Within the contract Pirelli has with the FIA as single supplier, there is provision for them to carry out up to 1000km of testing with any team – provided every team is offered the opportunity to do so.
"Pirelli and Mercedes were advised by the FIA such a development test could be possible if carried out by Pirelli, as opposed to the team that would provide the car and driver, and that such tests would be conditional upon every single team being given the same opportunity to test in order to ensure full sporting equity.
"Following this communication, the FIA received no further information about a possible test from Pirelli or Mercedes.
"Furthermore, the FIA received no confirmation that all teams had been given an opportunity to take part in this test."
Nothing much is likely to happen before next month's world motorsport council meeting and even then this result is likely to stand. But the mood in the paddock was far from celebratory.
Red Bull and Ferrari claimed that Mercedes had conducted three days of track testing on 15, 16 and 17 May. Nothing wrong with that, according to Toto Wolff, the sporting director of the Mercedes F1 team. He said on Sunday : "What we did was exactly to the rules. I don't know exactly where the complaint came from. I think it came from a triple world champion [Red Bull], and we're digging ourselves out of shit. We have just got out of shit and then we get a complaint like this. It's not how it should be."
Wolff denied the testing had been covert. "We stayed in Barcelona with the whole equipment, with the whole garage, with the trucks, with everything. There wasn't anything under cover. There was nothing we wanted to keep a secret. We didn't Tweet. Should we have?
"The team have gone through difficult times in the past years and nobody and nothing can take that win away from us today." But was he certain of that? "If a penalty comes we have to see. But for us it is about the sustainable long-term building of the team. We were asked by Pirelli [to help with testing] and as far as I understand the FIA give the OK to do this. So it's all according to the rules. And if other teams seek to clarify, let's clarify."
It is almost inconceivable that Mercedes would have gone ahead with testing in Barcelona without permission from the FIA – but that permission may have been granted against the FIA's own rules. Even before the race had started Christian Horner, Red Bull's team principal, had accused Mercedes and Pirelli of using "underhand" tactics.
Horner said: "What annoys me is that it was so underhand. And it makes a mockery of the rules. We have recently spent three hours in Bernie Ecclestone's bus discussing eight days of in-season testing for next year and it is already going on."
Red Bull had a good race day, extending their lead in the drivers' and constructors' championships with Sebastian Vettel and Mark Webber coming second and third. But that did not seem to console Horner, who said: "We have protested because we did not feel that it was right or in line with the regulations and Ferrari have also submitted a protest.
"We have presented why we feel that testing in Barcelona in the current car with the current tyres is in breach of the regulations. It is now with the stewards, so we will have to see what the outcome is. I will expect it will be referred to the world motor sport council. The regulations are black and white.
"I can understand why Pirelli would want to test and why the FIA might want that but there is a process which has not been followed. It was not in order for a team to conduct tyre testing in a current car, with current drivers on a current circuit with tyres that are going to be used at the next grand prix."
The Pirelli motorsport director Paul Hembery claimed the test was above board and he does not believe Mercedes gained any advantage. "It's completely regular in that we are allowed to do a 1,000-kilometre tyre test with any team," he said.
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