By Alan Baldwin
LONDON (Reuters) - Lewis Hamilton's Mercedes team and tire supplier Pirelli could face heavy sanctions after Formula One's governing body summoned them to an international tribunal for allegedly carrying out a 'secret' test in breach of the rules.
The governing International Automobile Federation (FIA) said in a statement on Wednesday that they had decided to act after conducting a full enquiry into the test that took place in Spain between May 15-17.
Mercedes used their current race car with Britain's 2008 world champion Hamilton and Germany's Nico Rosberg - the winner from pole position in Monaco on May 26 - sharing the driving over three days.
Rivals have accused the team of gaining a significant competitive advantage from the test and behaving in an 'underhand' fashion.
Pirelli dispute that, saying they were testing tires for 2014 and Mercedes did not know what compounds were being used.
Article 22.1 of Formula One's 2013 sporting regulations bars in-season testing with "cars which conform substantially with the current Formula One technical regulations in addition to those from the previous or subsequent year."
However, Pirelli are allowed, under their commercial contract, a number of 1,000km tests and have previously used a 2010 Renault which they say is some four seconds a lap slower than the 2013 machinery.
Ferrari, who conducted a similar 1,000 km test at the same Barcelona circuit in April but with a 2011 car and test driver, faced no further action because they were not deemed to have contravened the regulations.
No time was set for the tribunal, which could impose stiff sanctions against Mercedes if they are found to have acted illegally.
Already under fire for their quick-wearing 2013 tires, Pirelli have been pressing to be allowed to test with more up-to-date cars to that they can prepare for the significant challenge of a new V6 engine next year.
The Italian company has yet to agree a contract with the teams and FIA for 2014, however, which has added to their frustration.
Ferrari and world champions Red Bull had made official protests at last month's Monaco Grand Prix when word about the Mercedes test first filtered out, catching other teams by surprise.
It subsequently emerged that Ferrari had also conducted a test from April 23-24 - before the Spanish Grand Prix won by Ferrari's Spanish driver Fernando Alonso.
The Monaco stewards sent a report to the FIA who then sought further information from Pirelli, Mercedes, Ferrari and other teams.
The FIA said its president, Frenchman and former Ferrari team principal Jean Todt, had decided to close the case regarding Ferrari because the use of a 2011 car "is not deemed to contravene the applicable FIA rules."
In the case of Mercedes, the FIA statement said Todt found that "it results from the inquiry that the conditions of this testing may constitute a breach of the applicable FIA rules.
"The FIA International Tribunal is called upon to make a decision in compliance with the FIA Judicial and Disciplinary Rules," it added.
(Editing by Ed Osmond)