Apple Inc. has applied for a trademark in Japan for "iWatch" as rumours suggest it might be developing a smart wristwatch.

A document obtained Monday from the Japan Patent Office's website said the application was made June 3 and made public June 27.

It was not immediately clear when the application might be approved. Patent office and Apple officials in Japan were not available for comment late Monday.

Apple is rumoured to be working on a smart watch that would run on a version of the operating system used by its iPhone and iPad.

The company has not confirmed those rumours, but CEO Tim Cook has hinted that it may be developing a wearable computing device such as a wristwatch.

At the  D: All Things Digital technology conference in May he called the area of wearable technology  "ripe for exploration."

"I think the wrist is interesting," he said at the time when asked what type of products might be successful.

Applying for a trademark in Japan isn't proof of Apple's intentions. The company based in Cupertino, Calif., has many patents for devices it will never produce.