Some of Ferrari's Formula 1 rivals are reportedly upset with the Maranello based team.

According to Auto Motor und Sport (Germany) and the Swiss newspaper Blick, the unnamed rival teams are unhappy that Ferrari arguably abused the rules to test recent car upgrades.

One update was run during Pirelli's post-Spanish GP tyre test, while reports reveal that a new front wing and floor was tested last week at Ferrari's private test circuit at Fiorano during a 'filming day'.

"Neither is directly in conflict with the regulations," said Auto Motor und Sport correspondent Michael Schmidt, "but one can see that the spirit of the rules was violated."

Veteran F1 journalist Roger Benoit went one step further, headlining his Blick article on the issue with: "Did Ferrari cheat with new parts on a filming day?"

Carlos Sainz defended his team.

"We tested tyres (in Barcelona) that are used without electric blankets," said the Spaniard. "I don't think we can learn much from that.

"There's always things that you can try with your driving, but it's not like you can actually really test anything or put something in place for the race weekend."

As for the FIA, single seater director Nikolas Tombazis commented: "A comparison test of different versions (of parts) would not be allowed."

Schmidt, however, pointed out that no Ferrari rival has lodged a complaint, and the FIA is not currently investigating the matter.

Benoit added: "The FIA is said to be relaxed about it, as Ferrari claims they didn't swap out any parts during the filming day. So they just drove with the new parts."