The FIA, F1's governing body, has announced that Mercedes will have to appear before the International Tribunal following the tyre test it conducted with Pirelli after the Spanish Grand Prix.
News of the 'secret' test emerged on the Sunday of the Monaco Grand Prix weekend. Both Red Bull Racing and Ferrari lodged a protest with the stewards in Monte Carlo, with the matter being referred to the governing body.
Following that revelation, it also emerged that Ferrari had been involved in a similar test between the races in Bahrain and Spain, with that test again taking place at the Circuit de Catalunya.
Crucially however, Ferrari's test was carried out using a 2011-spec car run by its Corse Clienti division, and the case against the Scuderia has now been dismissed. The Mercedes test though used a 2013-spec car and after its initial inquiries the FIA has said this 'may constitute a breach of the applicable rules'.
A date for the tribunal has yet to be confirmed, but Mercedes could face a range of punishments, from a heavy fine, to a loss of championship points or even suspension from the championship – although the latter is very unlikely.
The full FIA statement, issued on Wednesday evening, read:
"The Monaco Grand Prix Stewards raised in their report to the FIA an issue concerning a tyre testing session carried out by Pirelli with the participation of Team Mercedes AMG Petronas F1 in Barcelona on 15-17 May 2013.
The FIA requested clarifications from Pirelli and Team Mercedes AMG Petronas F1 in this respect.
The FIA also asked questions to Scuderia Ferrari Team, which took part in a tyre testing with Pirelli in Barcelona on 23-24 April 2013.
The FIA requested all the other F1 Teams to provide the FIA with information they may have regarding any tests carried out by Pirelli during the 2013 season.
In the light of all the replies received and in view of the information gathered during this inquiry, the President of the FIA, acting as the FIA prosecuting body, has decided: