LONDON -- Michelin has come up with a new tire that should allow Williams and McLaren to fight Ferrari for the Formula One title without fear of disqualification, the governing FIA said on Tuesday.

Calling time on a bitter argument over allegedly illegal tires, the International Automobile Federation (FIA) said in a statement before Sunday's Italian Grand Prix that they were satisfied with what they had seen.

"The FIA were shown examples of a new Michelin tire before and after use," said the statement, released after a meeting with Michelin, McLaren and Williams bosses on Monday.

"The FIA technical department has confirmed that it believes these tires will comply with the Formula One regulations if used in the same way at Monza."

Williams, who lead Ferrari by eight points in the constructors' standings, and McLaren fear a clampdown on the tire rules at Monza could hand Ferrari's Michael Schumacher a record sixth title by disqualifying their drivers.

Both teams are supplied by Michelin, while Ferrari use Bridgestone tires and have accused the French manufacturer of making front tires that had an illegal amount -- more than 270 millimeters -- of tread in race conditions.

"Potentially, this whole affair is throwing the world championship out of the window for both of us," Tuesday's Guardian newspaper quoted McLaren managing director Martin Whitmarsh as saying.

The FIA made clear that although they had not changed or reinterpreted the rules, the Michelin tires used previously might not pass post-race inspection.

"With hindsight, it is regrettable that those using the earlier Michelin front tires did not consult the FIA about possible excess tread width as soon as they became aware of it," said the statement.

"However as far as the FIA technical department is concerned, the matter is now closed and the championship can continue with all teams on an equal footing."

Michelin tested with the new tires at Monza last week after the FIA said it will now check tires for tread width after the races as well as before. Some teams suggested afterwards that the new tires performed better than the old ones.

The title battle is at a critical stage with Schumacher leading Williams' Colombian Juan Pablo Montoya by one point with Finland's Kimi Raikkonen a further point behind for McLaren with three races remaining.

Whitmarsh said McLaren and Williams still had "considerable concern about the issue of approving the tires' conformity at the end of the race."

"Put simply, we can either use the existing tires and risk not conforming with these revised rule interpretations or we can use new tires and still risk being illegal despite a loss of performance," he added.

"Michelin has done a great job but the changes in setup we have had to make -- to toe-in, camber and tire pressures -- have not worked to our advantage."

However Williams' chief operations engineer Sam Michael sounded less worried, saying that the meeting with the FIA was "very constructive for all those concerned."