BAR have scuppered test driver Anthony Davidson's chances of racing for Williams in Formula One next year.
Davidson was due to attend a Williams test day next week
Davidson was due to test with Williams in Spain next week as they try out candidates to replace Ralf Schumacher and Juan Pablo Montoya.
But BAR technical director Geoff Willis said Williams had set "untenable" conditions for the 26-year-old.
"Anthony is one of the team's prime assets and we have him under long-term contract," said Willis.
"It is for this reason that a great deal has been invested
in him over the years and whilst we are enormously keen for him
to gain F1 race experience and further his career, we clearly
cannot compromise the future of BAR.
"In that regard, we felt that we had reached a very good
agreement with Williams whereby he could drive in 2005, but
could be repatriated to BAR under certain specific circumstances
"Williams have insisted on an unconditional arrangement
which, unfortunately, is untenable for the team."
A Williams spokesman said: "All we asked BAR for was the opportunity to retain Anthony as a race driver in 2006 if BAR were unable to offer him a race seat."
The development further strengthens the likelihood that Antonio Pizzonia will be Mark Webber's team-mate at Williams in 2004.
The team are due to test Jordan driver Nick Heidfeld next month, but Brazilian Pizzonia, who scored points in two substitue appearances in 2004, is understood to be a strong favourite for the drive.
David Coulthard's chances of a return to the team for whom he made his F1 debut in 1994 are thought to be slim.
In October, BAR won another fight with Williams over the future of British driver Jenson Button.
A contractual dispute was decided in BAR's favour following a ruling by Formula One's Contract Recognition Board (CRB).