MOUNTAIN VIEW, Calif. -- Google is offering $10 million in prizes for people who build the best software for its upcoming cell phone operating system.

The Mountain View Internet search leader is developing a free cell phone software package that it says will make it easier to surf the Web over mobile devices.

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It also will give Google more opportunities to sell ads and services.

The system will be based on computer code that can be openly distributed among programmers.

As part of the Android Developer Challenge, a panel of judges will pick 50 winners from entries received early next year.

The original operating system announcement ended months of speculation about the Mountain View-based company's cellular ambitions.

Google won't be making the phones, nor does it plan to stamp its brand on the devices.

Four cell phone manufacturers have agreed to use Android in some of their phones.