The future of Michael Schumacher in F1 is uncertain after the news that the German is to leave his role with Mercedes at the end of the year.

The seven-time champion came out of retirement to join Mercedes at the start of the 2010 season, inking a three-year deal to form an all-German line-up alongside Nico Rosberg.

However, the past three seasons have failed to see Schumacher achieve the kind of results that saw enjoyed earlier in his career, with just one podium finish - in Valencia earlier this year.

Speculation has suggested that the 43-year-old could retire for a second time while rumours have surfaced that he could be approached by Sauber, who need to find a replacement for McLaren-bound Sergio Perez and who worked with Schumacher when he was competing in Sportscars prior to making the move into F1.

Speaking following the announcement that Lewis Hamilton is to replace him next year, Schumacher admitted he was disappointed that his time with the team hadn't delivered the desired results and said he was focused on the best results possible through the remainder of the season.

"I have had three nice years with the team which unfortunately did not go as well as we all would have wanted on the sporting side," he said. "I wish Lewis well and for the team to achieve the success we worked so hard for in the build-up. I would like to thank the team for their trust and all the guys for their unconditional commitment. I will now concentrate on the next races."

Team boss Ross Brawn, who worked alongside Schumacher at both Benetton and Ferrari, thanked him for the contribution he has made to the programme over the past three seasons.

"On behalf of Mercedes AMG Petronas, I would first of all like to thank Michael Schumacher for the important contribution he has made to the growth of our team over the past three seasons," he said. "His energy and commitment have never wavered, even when results have not matched our own expectations, and we are determined to finish the 2012 season together on a high. As always, it has been a pleasure to work with Michael."