Ferrari has hit back at claims that it is also being investigated by the International Automobile Federation for alledgedly illegally testing with Pirelli.In May 2013 Wheels24 reported that the IAF, Formula 1's governing body, was investigating Mercedes' "secret" Barcelona tyre test. Ferrari and Red Bull launched a protest after the following 2013 Monaco GP when it emerged that Mercedes had tested Pirelli tyres with its 2013 car after the 2013 Spanish GP in May. 'RULES ALLOW IT'It was believed only Mercedes was under the spotlight for its “secret test” but in June 2013 the IAF revealed it was also looking into Ferrari's recent Barcelona test.Ferrari spokesman Renato Bisignani said: "There is nothing wrong with using a two=year-old car, the rules allow it."Another Ferrari spokesman added: "We have never tested with the 2013 car." Indeed, it is believed that the 2011 Ferrari used for the Pirelli test was actually owned privately and operated by the Corse Clienti department, not the race or test team.Test driver Pedro de la Rosa was at the wheel.Mercedes' Toto Wolff, referring to the IAF investigation, said: "We have until this week to answer a series of questions."