Unveiled at the Web giant's I/O developer conference, Android Pay enables in-app and NFC-based payments with handsets running the KitKat version of the OS at around 700,000 US locations. And for some firms, loyalty programmes and special offers will be automatically applied at checkouts.

With the newest version of Android, M, offering standardised support for fingerprint authentication, users will be able to unlock their phones with the push of a digit and tap a contactless reader for real-world transactions. In addition, open APIs mean that developers can build fingerprint authentication into their apps and enable customers to make purchases with a finger.

With Visa, MasterCard, American Express and Discover all onboard, customers add a card and a virtual account is created which is used to process payments, meaning retailers do not get access to card information. Users can activate Android Pay through Google's app or through any supporting bank app.

USAA and US Bank are among the first clutch of banks to declare their support for Android Pay and the app's fingerprint authentication feature.

“We’re committed to delivering simple and secure payment experiences for our members, which is why we are moving so quickly to integrate our cards with Android Pay,” says Vikram Parekh, assistant vice president of credit card development at USAA.

Meanwhile, with Wallet having suffered thanks to a lack of support from mobile network operators, Google is taking advantage of its recent acquisition of telco-owned rival Softcard to make sure that any Android handset bought through AT&T, T-Mobile or Verizon supports Android Pay out of the box.

Dave Burke, VP, engineering, Google, says: "We believe that the same partnership model which fuelled Android's growth from a single device seven years ago to now more than a billion users will enable Android Pay to be successful too.

"And we're working closely with payment networks, banks and developers to bring mobile payments to Android users around the world, with a roll out starting in parallel to launching M this year."

After its false start, Google is hoping that Android Pay will help it in the mobile payments battle with rival Apple, which launched its similar service last year and has seen strong adoption.

However, one potential problem for Google is handset giant Samsung, which will soon muddy the Android waters with its own wallet based on technology picked up through the recent acquisition of LoopPay.

Separately, Google has also confirmed that it will introduce click-to-buy buttons in video ads on YouTube, and across the company's search engine, in a move that is seen as a direct shot against Amazon's one-click online retail business.