Williams has confirmed that it will end its engine deal with Toyota at the end of the current F1 season.
Toyota stepped in to supply engines for the Grove-based team at the start of the 2007 season after a tough 2006 campaign running Cosworth motors – which saw the team fail to finish on the podium all year for the first time since 1977.
While the partnership with Toyota failed to carry Williams back to the kind of title-winning form it enjoyed in the 1990s, the team returned to the podium and took fourth in the constructors' championship in 2007 with another two podiums following in 2008 thanks to Nico Rosberg.
This season however, speculation has mounted that Williams wasn't happy with the potential of the Toyota engine and was keen to end its deal to look at alternatives for next season.
Toyota president John Howett revealed at Suzuka that the team had requested to be released from its customer deal – stating that the Japanese manufacturer was 'happy to supply Williams but they don't want our engine' – and Williams has now confirmed that the deal will end at conclusion of the current season.
"At a time of great difficulty for us as a team, Toyota stepped forward and agreed to supply us with engines for 2007 through to the end of 2009," Williams team principal Frank Williams said.
"Toyota has been a very decent partner who have always respected our independence and provided us with a first-rate technical product. 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.
"I would like to single out for our thanks the Toyota engineers and technicians who have worked within our race team tirelessly for the past three years."
Tadashi Yamashina, Chairman of Toyota Motorsport, added that the Japanese company respected the decision taken by Williams, which has seen the deal brought to an end by mutual consent.
"We have enjoyed a productive working relationship with Williams and I believe both companies have benefited from that partnership," he said. "We respect the wishes of Williams to look for other opportunities and wish them well for the future."
Williams states it will confirm its engine partner for 2010 in due course, with speculation suggesting that a return to Cosworth is the likely option.