Visa Inc. may be preparing to debut its ties to Google Inc.'s mobile wallet in London at the 2012 Summer Olympic Games, sources say.

When Google Wallet launched in the U.S. in September with MasterCard Inc. as its first partner, Google said it had reached agreements with all the major card brands to join the effort. But it provided no timeframe for Visa, American Express Co. and Discover Financial Services to come aboard.

European media last week reported that Google Wallet is lining up retailers and banks to participate in a test of the mobile-payments technology in London as early as the first quarter of 2012, in time for the Olympics.

Google declined to comment on those reports.

Sources close to the situation now say Visa, the payments sponsor of the London Olympics, is likely to be one of the partners involved in the Olympics effort.

A Visa spokesman declined to comment on Google Wallet rollout plans. The spokesman says that Visa earlier this year signed a global licensing agreement with Google for Visa's payWave NFC technology.

"Ultimately this paves the way for Visa cards to be used in Google Wallet but it's up to issuers to determine which cards would be offered in the wallet," he says.

Spotlighting Google Wallet at the Olympics could be a coup for the Near Field Communication-based payment scheme because "it would illustrate for people on an international stage, in a confined space, what mobile-payments is like," says Bryon Morrison, president of wireless at the promotion firm The Marketing Arm in Dallas.

The timing could go a long way to helping boost interest in Google Wallet as more analysts are saying NFC-based mobile payment is overhyped.

Google Wallet launched in the U.S. in September with partners that included Sprint Nextel Corp., which is making the mobile-payment service available through the Nexus S smartphone; Citigroup Inc.; MasterCard; First Data Corp.; and about a few dozen merchants.

Customers may fund Google Wallet with a Citi-issued MasterCard or a Google-branded prepaid account, which can be funded from other payment cards.

In recent days, Google has come under heightened scrutiny for a potential security gap that experts say enables storage of sensitive customer data inside mobile handsets.

And Verizon Wireless this month made clear that it is not including Google Wallet in its new Samsung Galaxy Nexus smartphone, which Morrison says is "not positive" for broad NFC adoption.