Red Bull Racing team principal Christian Horner has hit out at Ferrari and has said that use of a 'filming' day to test its new blown diffuser system ahead of this weekend's European Grand Prix was 'a bit naughty'.

Although the Maranello-based outfit did not break the rules when it ran at its own Fiorano test track last week, the consensus amongst the other teams is that the 'promotional' event was certainly against the spirit of the test ban.

Indeed McLaren boss, Martin Whitmarsh was similarly unimpressed [see separate story - click here], and there are calls now to clarify the agreement and stop a repeat.

"Ferrari managed to sneak a filming-day test in last week, which is a bit naughty," Horner told British newspaper, The Daily Telegraph. "It was arguably within the letter of the laws but not within the spirit.

"You don't just run these cars - there has to be a lot of planning - and it wasn't by mistake that they happened to run on that day with the new exhaust system.

"They managed to have a look at it, and they've probably learned a bit. I'm sure there will be a lively debate at the next team principals' meeting. I think it's something that needs to be tidied up, because it's effectively a gentlemen's agreement, and it's important that that should be respected."

Fernando Alonso meanwhile, who was driving during the 'filming' day, however, rejected suggestions that the Scuderia learned anything.

When asked about the run prior to practice on Friday, he joked; "The feeling [with the new updates] was very good and I was running behind a car with cameras so it was very good at 60kph, very stable.

"We also did some laps without a car in front but we had ten cameras on the car and on the helmet so it was not very comfortable to drive. It was also my first time driving a Ferrari Formula 1 car at Fiorano, so I really have no idea [how the updates affected the F10] but I think tomorrow [Friday] we will have a better answer."