Robert Kubica's remarkable F1 comeback with Williams ends with this season

Robert Kubica will leave former champions Williams at the end of the season, a move likely to bring the curtain down on the Polish driver's extraordinary Formula One racing comeback.

The 34-year-old made his race return this year after suffering near-fatal injuries, including a partially severed right arm, in a rally in Italy on the eve of the 2011 season.

"I am looking for different opportunities. In order to evaluate other opportunities, I have taken the decision that I will not continue more with Williams after this year," he told reporters at a Singapore Grand Prix news conference.

"It took ... a lot of time to recover and come back to the sport. I said this year will be a goal to remain in F1 ... but not at every cost.

"I have to first of all do what will bring me back a bit of joy of racing. This season has been very tough from a performance point of view, but it has been also very demanding. Being back in Formula One after a long time is not easy."

Williams is last in the championship after 14 races with an uncompetitive car and just one point scored by Kubica in Germany after drivers ahead of him were demoted by penalties.

The Pole, a race winner with now-defunct BMW-Sauber in Canada in 2008 and once seen as a potential champion, remains the only Polish driver to have competed in the Formula One championship.

Williams said it respected Kubica's decision and would announce it 2020 lineup in due course.

British rookie and last year's Formula Two champion George Russell is backed by engine provider Mercedes and is sure to stay, with Canadian reserve Nicholas Latifi seen as Kubica's likely replacement.

Latifi, who is second in the F2 championship, has put in three practice appearances for Williams.

Deputy team principal Claire Williams, daughter of co-founder Frank, has already marked the 24-year-old out as a contender.

Nico Hulkenberg, who is being replaced by Frenchman Esteban Ocon next season at Renault, could also be in the frame.

The German had been strongly linked to a move to Haas next year, but the U.S.-owned team is sticking with its lineup of Romain Grosjean and Kevin Magnussen.

Polish media reports said Kubica's sponsor, Polish oil refiner PKN Orlen, will also end its deal with Williams.

"At this stage ... we are considering different scenarios for the next season, as we want to choose the best one for both parties," PKN Orlen Chief Executive Daniel Obajtek was quoted as saying in a statement.

"We intend to stay in Formula One, strengthening the international recognition of the ORLEN brand."