Ferrari's technical director Ross Brawn has admitted it was the Italian team who blew the whistle on Formula One rivals Williams and McLaren for their alleged use of illegal Michelin tyres.

Following the Hungarian Grand Prix last month, the sport's governing body (FIA) said it had received information that Michelin's front tyres could be in breach of regulations.

"It was us who told the FIA at the end of the race that their treads were too big - we are not going to accept losing this way anymore," Brawn was quoted as saying in Wednesday's Gazzetta dello Sport.

Asked what advantage a wider tread gave to a car, Brawn said: "It gives a better balance to the front of the car when braking because of the distribution of weight, making it more efficient on the bends."

Brawn said Ferrari went to the FIA after Bridgestone came into the possession of some pictures taken in the paddock by a Japanese photographer in Budapest.

"They showed that the front Michelin tyres had an excessively large tread so we went to see Charlie Whiting (the race director)," said the 48-year-old Englishman.

"Then we sent the famous letter on the basis of the measurements and photos. We could have done nothing, not informed the FIA and then made a complaint at the next race, but that didn't seem like the right thing to do."

When a Michelin-shod car goes round a corner, its front tyres roll in such a way that a small part of their sidewalls come into contact with the track, which improves the car's grip.

The rules of Formula One state that the tread can be no more than 27 centimetres wide, but there are suggestions that a bigger area of the Michelin tyre may be gripping the road, giving them an advantage over Bridgestone.

Ferrari's Michael Schumacher, whose car uses Bridgestone tyres, has a slender one point lead over Williams in the drivers' championship with three races left.

The FIA has threatened to disqualify teams using these tyres at the Italian Grand Prix on September 14.

In Hungary 10 days ago, Fernando Alonso's Michelin-shod Renault actually lapped Schumacher's Ferrari -- an almost unheard-of incident in Formula One.

FIA president Max Mosley and Whiting, his technical delegate, visited the Ferrari factory in Maranello last week, where they met the president, Luca Di Monteze molo, the sporting director, Jean Todt, Brawn, Schumacher, and various engineers.

But Mosley denied Ferrari had blown the whistle.

"Charlie Whiting had already made it clear in Hungary that in future we would be looking at real tread width," Mosley told Britain's Guardian newspaper.

"We have reason to believe that the tyres in Hungary were not identical to those in use at the start of the season. There may also have been changes to the way those tyres are being used."

Michelin says it has supplied the same tyres at all the season's 13 races.