Williams have played down speculation that Canada's former world champion Jacques Villeneuve is poised for a Formula One comeback with them.

A spokesman said however that the BMW-powered team could be ready to make an announcement on next season's driver line-up by August.

British newspapers reported on Tuesday that Villeneuve, the 1997 champion with Williams who lost his drive at BAR at the end of last year, turned up at the Le Castellet test circuit in southern France.

The Sun newspaper reported that the 33-year-old, who has not attended a race all year, flew from Monaco by private jet and visited the Williams garage and former colleagues at BAR.

A Williams spokesman said however that the team, who could have two highly desirable vacancies for 2005 if Ralf Schumacher follows Colombian Juan Pablo Montoya out, had not invited Villeneuve.

"And to deny circulating rumours, he is not being seat fitted at the track for us this week or indeed testing for us in France," he added.

"In respect of our driver selections for 2005 and beyond, the team's immediate priority is to improve the performance of the FW26 as this will be the biggest single incentive to securing a competitive driver line-up.

"We are actively considering a wide range of potential candidates as would be reasonably expected and to this end we have had discussions with many drivers whose names have been the subject of recent press speculation.

"However...a discussion does not mean necessarily that a driver is under active consideration for any number of reasons.

"It is anticipated that the team may be in a position to confirm driver appointments by August.

Montoya's move to rivals McLaren in 2005 was announced last year and Williams have had discussions with many drivers, including Villeneuve, since then.

Australian Mark Webber, at Jaguar, is widely considered a favourite to replace Montoya but his contract situation is unlikely to become clear for some months due to performance clauses.

Ralf's contract expires at the end of the year and he has been persistently linked to Toyota.

The Le Castellet circuit is owned by Formula One supremo Bernie Ecclestone, who was instrumental in bringing the Canadian into Formula One with Williams and is eager for him to make a comeback.

"It's great that Jacques is having talks with Williams -- I've been trying to get him to do that for a long time," the Sun quoted Ecclestone as saying.

"I never felt Jacques should have left the sport in the first place and it would be fantastic to see him back."