Williams will continue to use Cosworth engines in 2011, company chairman Adam Parr has confirmed.
Williams is currently in the first season of a three-year supply contract with Cosworth, but had been linked with a Renault customer engine deal after coming close to signing with the French manufacturer last year.
"We are with Cosworth and I am very happy to confirm that that will continue next season," Parr told reporters at Silverstone on Thursday.
Cosworth has made improvements to its engine this season after friction between the two parties earlier in the year, and in last month's European Grand prix both Williams FW32s made it into Q3 in dry conditions for the first time.
But despite continuing with Cosworth, which returned to Formula 1 this year after three years on the sidelines, Parr is hopeful that the team will be able to secure a factory engine deal in the future.
"In the long-term, the best model for an independent Formula 1 team is to have a partnership with a car manufacturer that provides engines, some sponsorship and wants to go racing," he said.
"The team has had some fantastic partnership with BMW, Honda and Renault in the past and I think that's ultimately where we would like to go again."
Williams has used customer engines since its partnership with BMW ended after the 2005 season. Since then, its cars have been powered by Cosworth and Toyota units.