Amid the controversy about Mercedes' 'secret' Pirelli tyre test, F1's governing body on Friday said it is also investigating Ferrari.
At Monaco, Ferrari and Red Bull launched a protest when it emerged that Mercedes had tested tyres for Pirelli with its 2013 car and race drivers Lewis Hamilton and Nico Rosberg just after the Spanish grand prix last month.
But at the same time, it was rumoured that Ferrari had similarly tested, after Bahrain, but with a two-year old car and test driver Pedro de la Rosa at the wheel.
The FIA said late on Friday that it is investigating not only Mercedes, but also the Ferrari test.
In a statement, the Paris based federation said it has asked both teams "to reply to a disciplinary inquiry in pursuance of the FIA judicial and disciplinary rules".