(CNN) -- Formula One's governing body the FIA has told a tribunal in Paris that Mercedes did not get permission for an alleged illegal tire test with Pirelli, according to the sport's official website.
The German marque conducted a three-day, 1,000 km tire test with the sport's official supplier Pirelli in May.
The FIA launched an investigation after rival teams Red Bull and Ferrari lodged an official protest upon learning of the development test in Spain, which was reported by race stewards.
The tribunal has the power to impose fines and bans, including exclusion from the F1 world championship.
At the hearing in France, the FIA reiterated that it did not give official permission for the test and argued that Pirelli had not offered other teams the chance to participate.
It said although FIA race director Charlie Whiting had suggested a test was possible if all teams were offered the chance to take part, that did not represent an agreement.
According to the FIA, Mercedes could have fallen foul of the International Sporting Code which prevents: "Any fraudulent conduct or any act prejudicial to the interests of any competition or to the interests of motorsport generally."
Mercedes insisted the test had been conducted by Pirelli and not them, and as such, they had not broken the rule which states: "Track testing shall be considered any track running time not part of an Event undertaken by a competitor entered in the Championship."
The German team also claimed that if the test they took part in had breached the rules then so had one conducted by Ferrari. They claimed the Italian team had discussed tire data from the test with Pirelli.
Mercedes' rivals objected because it used race drivers Lewis Hamilton and Nico Rosberg to carry out the test in the team's 2013 car -- and it is primarily for these reasons the sport's governing body has brought the case before its tribunal.
Rival teams have accused Mercedes of gaining a significant competitive advantage from the test and of conducting it in secret two days after the Spanish Grand Prix, where both Rosberg and Hamilton suffered tire problems despite the German having started in pole position for the second successive race.
Mercedes team principal Ross Brawn stressed his team could not have prospered from the test data.