The Formula 1 tyre controversy may yet take an even more serious turn after Ferrari revealed to Autosport magazine that it is considering taking further retrospective action against Michelin teams.

The sport's governing body, the FIA, has changed the way that it measues tyre tread from the next round of the championship in Italy, but Ferrari technical director Ross Brawn has admitted that the team may appeal the results of previous races.

Brawn told Autosport: "We're not sure that the matter is closed. Measurements were taken after the Hungarian race that clearly showed that there were tyres above the legal limit and we've got to see what happens because we're not happy with that situation."

Brawn pointed out that the FIA can investigate past problems if new information comes to light. That may make it possible for Ferrari to protest all 2003 results to date. Brawn says that Ferrari is looking at photographic records to try to establish for how long Michelin tyres have been being used in the disputed manner.

"We just want a fair playing field," added Brawn, " and it was clearly not a fair playing field."