Symbian, overwhelmingly the most-used mobile phone operating system, would welcome Google to contribute to Symbian’s open source program, the company said. But then, Symbian would welcome anyone.

News stories out of Japan prompted speculation that Symbian and Google somehow might get together to develop a new handheld OS. An official statement from Symbian later emphasized that Google already develops applications for Symbian’s system, including Google Maps, YouTube and Gmail, but is not cooperating at the OS level.

Nokia recently acquired 100% ownership of Symbian and announced plans to turn it over to a new Symbian Foundation as part of a move to create an open-source operating system for handsets. The OS will be offered free to foundation members, probably sometime in the first half of 2009.

Symbian’s official statement today said the foundation “will welcome any organization that wishes to join and contribute toward the development of the Symbian Foundation platform. On that basis, Google will be welcome to join the Foundation, as with any organization that agrees to the Foundation’s terms and conditions of membership.”

Symbian’s current CEO, Nigel Clifford, was quoted in a story out of Tokyo as saying he thought the Symbian Foundation’s open-source plans accomplished what Google has wanted to do with its Android platform. Android, built on Linux, is being developed by the Open Handset Alliance, with phones expected to be available later this year.