Five of the seven Michelin-contracted Formula One teams have approached rivals Bridgestone about a possible switch in 2006, the Japanese tyre company said on Wednesday.
Michelin have won all but one of the season's 12 races to date but their image was dented by last month's US Grand Prix fiasco when none of their teams competed due to tyre safety concerns.
A Bridgestone spokeswoman, speaking before Sunday's Hungarian Grand Prix, said the approaches were to be expected at a stage in the season when teams were reviewing contracts.
Michelin currently supply championship-leaders Renault, McLaren, Williams, Toyota, BAR, Red Bull and Sauber while Bridgestone have just champions Ferrari with struggling Jordan and Minardi.
The French company said in a statement earlier this month that they had been approached by one of Bridgestone's three teams but would be happy to supply fewer in 2006.
"We weren't surprised to read the Michelin statement but the facts are that we have been approached by five non-Bridgestone teams," said the spokeswoman, who gave no names.
"If we do secure further teams it will be on the basis of mutually agreeable commercial terms."
Privately-owned Red Bull are widely expected to switch supplier after agreeing to run Ferrari engines next year.
Toyota have a long-standing commercial association with Bridgestone in Japan but technical director Mike Gascoyne has hinted he wants the team to stay with Michelin.
A likely change in the qualifying format next year could play to Bridgestone's strengths however, with a return to multiple-lap sessions rather than the current single lap that has favoured Michelin.