A tyre testing session involving Mercedes and Pirelli that was criticized by rival Formula One teams will be referred to the FIA's international tribunal as a possible breach of the sport's rules.
The ruling International Automobile Federation (FIA) said in a statement Wednesday that it had looked into the Mercedes tyre session held in Barcelona from May 15-17 - and another test involving Ferrari in Barcelona during April. The inquiry included asking all F1 teams about any tests they may have carried out with Pirelli this season.
The FIA said it had decided to close the Ferrari case because the Italian team had used its 2011 car - which was "not deemed to contravene" the rule."
However, it will bring the case against Mercedes because "it results from the inquiry that the conditions of this testing may constitute a breach of the applicable FIA rules." It added that the tribunal "is called upon to make a decision in compliance with the FIA Judicial and Disciplinary Rules."
Pirelli's tests with Mercedes led to protests from Red Bull and Ferrari during the Monaco Grand Prix, which was won by Mercedes driver Nico Rosberg.
The tyre manufacturer subsequently denied any breach of the rules and said it believed the tests offered no advantages to the German team.
Pirelli motorsport director Paul Hembery said last week that the tyre compounds tested are not going to be used in the 2013 season.
"The tests were performed on tyre specifications not used and will not be used in the 2013 world championship. The focus was on 2014," Hembery said. "These tests were actually performed blind. Mercedes had no idea and has still no idea what was being tested. There was no benefit to them. The benefit was for Pirelli and F1 in general."