Jenson Button broke his silence on Monday to spell out the reasons behind his controversial and contested decision to leave the BAR Formula One team for Williams.

The 24-year-old Briton, caught in a tug-of-war for his services, said he was confident the move would go ahead after Williams submitted paperwork to the sport's Contract Recognition Board (CRB).

While leaving several questions unanswered, Button, who announced he was leaving BAR last month, insisted his had not been a snap decision. He said it had nothing to do with money and all to do with his determination to be Formula One world champion.

"I don't think BAR is the right place to be next year because I don't think they will be able to challenge for the championship," he told a news conference at a London hotel.

"I think that Williams in future is the team to be with. They've got the resources and Mark Webber and myself will be a great team.

"Continuity is important but if you're not sure which direction the team is going, it's very difficult to be happy there," he added of Honda-powered BAR.

FANTASTIC TEAM

Button praised BAR as a 'fantastic team' but said that, despite appearances to the contrary, he had not been 100 percent happy there this year.

The Briton said that financially he would have been 'substantially' better off staying, particularly after owners British American Tobacco offered him more money to stay but Williams offered greater career potential.

"A Formula One driver's career has to keep moving," he declared. "I can't keep finishing third or fourth in the championship."

"Money is not my aim in Formula One. My reason for moving to Williams is to be world champion."

Button is third in the championship with four races remaining. He has had seven podium finishes this season.

BAR also have a contract filed at the Swiss-based board and both teams have an obligation under the sport's guiding 'Concorde Agreement' to respect the CRB's ruling.

While the board is independent from the governing International Automobile Federation, the FIA will issue a super-licence only to a driver whose contract is recognised.

The next stage in the Button saga is for a 'conflicting contracts meeting' to be held at the CRB in Geneva, probably within the next two weeks, with a decision soon afterwards.

Asked whether he could envisage continuing with BAR if the board recognised that contract as binding, Button refused to speculate.

BMW-powered Williams, who gave Button his F1 debut in 2000, believe their two-year deal is water-tight and a spokesman said the delay in registering the contract was solely to allow private negotiations to continue.

The delay had triggered fears that the dispute could rumble on beyond the end of the season in October and end in the law courts.

Williams have also signed Australian Mark Webber from Jaguar in an all-new line-up for 2005 to replace departing Ralf Schumacher and Juan Pablo Montoya.