Seven-time world champion Michael Schumacher is still "undecided" over his future after learning that he will be replaced by Lewis Hamilton at Mercedes, according to his agent Sabine Kehm.

"Michael could have re-signed (for Mercedes) this summer if he'd wanted to," Kehm told AFP.

"He wasn't sure of what he wanted to do and that hasn't changed since."

Mercedes announced on Friday that British driver Hamilton had signed a three-year deal to drive for the German stable from 2013, replacing Schumacher.

Hamilton will drive alongside Nico Rosberg, who will be in his fourth year at Mercedes and won his first Formula One race this year in China.

Schumacher, 43, enjoyed three years at Mercedes, although he accepted that results had been disappointing.

Schumacher's options will be to continue racing in F1 -- in which he has shown some thrilling form, fitfully, this year -- and he could be a target for Sauber, with team owner Peter Sauber a close friend.

Indeed, Sauber was seen deep in conversation with Schumacher's agent Kehm at the Italian Grand Prix earlier this month.

Schumacher, however, has also been linked with a return to Ferrari.

But with his family home in Switzerland, a final hurrah at Sauber, if not a move into Mercedes' management team, seems more likely.