Security researchers said they found a vulnerability in the Google Inc mobile payments platform which is currently available in phones sold by Sprint Nextel Corp.

Mobile payment services that allow consumers to pay by waving their phone at a check-out terminal, instead of using a credit card, have long been available in Japan and some other countries but are only just emerging in the United States, says a Reuters report.

The alleged vulnerability in the Google Wallet was identified by Joshua Rubin, a senior engineer with zvelo, a security firm in Greenwood Village, Colorado, the report says.

Rubin developed an app dubbed Wallet Cracker that he says can break the four-digit PIN required to launch the Google Wallet app. He demonstrated how it works in a video on his blog (bit.ly/zgO2L6).

Rubin said that he had disclosed his findings to Google and that the company "was able to confirm the issue and agreed to work quickly to resolve it," the report notes.

Google spokesman Jay Nancarrow in an emailed statement said "We are working to resolve the issue," even as he took issue with the study that prompted the allegations, says the Reuters report.

"The zvelo study was conducted on their own phone, on which they disabled the security mechanisms that protect Google Wallet by 'rooting' the device," Nancarrow said.

Google, he added, recommends that people not install Google Wallet on "rooted" devices and that they should set up a screen lock as an additional layer of security, the article says.