By Alan Baldwin

SUZUKA, Japan (Reuters) - McLaren will 'never say never' to Lewis Hamilton returning to them one day even if that looks unlikely at the moment, team principal Martin Whitmarsh said on Friday.

Hamilton, McLaren's 2008 Formula One world champion, has signed a three-year deal with rivals Mercedes and will take retiring Michael Schumacher's place there at the end of this season.

The British driver assured reporters ahead of this weekend's Japanese Grand Prix that he was not leaving McLaren through the back door and that the path he had chosen to take could ultimately bring him back.

"Yes, certainly, I think it is (possible)," Whitmarsh said. "But he's joining a strong team in Mercedes and I don't think he'll be coming back any time soon.

"I'm sure they've got a good contract... and I don't think Lewis's intention is to hop from team-to-team on an annual basis.

"But never say never and we'll see what happens in the future," he added.

There is a notable precedent for Hamilton, with four times world champion Alain Prost starting his Formula One career at McLaren in 1980 before moving to Renault for three years and then returning to win titles.

Hamilton's 2007 team mate Fernando Alonso, now the championship leader with Ferrari, moved to McLaren from Renault and then went back to his previous team after an ill-fated season.

Whitmarsh also played down a suggestion by Hamilton on Thursday that he knew all about next year's McLaren, with the driver telling his Mexican replacement Sergio Perez that it was sure to be good.

"I think he knows the people and what we're trying to do but I don't think there's any great secrets in that," he said.

"I think if I was pursuing intellectual property from other teams, I'd probably go for engineers not drivers."

(Editing by John O'Brien)