Former Formula One champions Williams will have a new engine partner next season after announcing the end of their Toyota deal on Wednesday.

Toyota has been a very decent partner who have always respected our independence and provided us with a first-rate technical product, said team owner Frank Williams in a statement.

We are proud that we have been able to work with such a great company, and we are grateful to the team in Cologne for their support.

Williams said the new partner, widely expected to be their former supplier Cosworth, who are returning to the sport after a three-year absence, would be announced in due course.

Cosworth will also be providing engines to four new teams in 2010. Renault would be another alternative for Williams, who won championships with the French manufacturer.

Toyota, whose own team are ahead of Williams in the standings, said in a separate statement that a contract extension agreed earlier this year had been terminated at Williams' request.

We have enjoyed a productive working relationship with Williams and I believe both companies have benefited from that partnership, said Toyota team principal Tadashi Yamashina.

We respect the wishes of Williams to look for other opportunities and wish them well for the future. (Reporting by Alan Baldwin; editing by Peter Rutherford)