Rossi's first 84 starts in the showcase class yielded 45 victories

Rossi has already test driven for Ferrari and there has been continual speculation in the Italian press that he will replace Michael Schumacher.

The 26-year-old has frequently said that he would like a new challenge in motor racing but recently claimed: "I'll finish my career in motorcycling.

"I've said nothing new and still new things are being written," he added.

Rossi's Yamaha colleagues are not convinced, however, with team director Davide Brivio quoted in the Italian press as saying the Italian would be in Formula One from 2007, although he later denied making that remark.

Speculation is likely to continue at Rossi's home Grand Prix in Mugello on 5 June, but some observers believe he is likely to agree a new deal to stay with Yamaha for the 2006 season.

Rossi was an instant success, winning the 125cc class as a teenager in 1997, and adding the 250cc crown two years later.

Having won three titles in the top class with Honda, in 2003 he chose to leave the team for Yamaha, but quickly added a fourth successive title last year.

A fifth this year looks very likely as he has already won three of the first four rounds.