Google, the world's leading search engine, officially launched on Monday Google Wallet, allowing users to pay by tapping NFC-enabled Android phone against a compatible card reader.

According to a Google blog post, the mobile payment app will be pushed to all Sprint Nexus S 4G phones through an over-the-air update.

Google Wallet currently allows users to pay with Citi MasterCard credit card and Google Prepaid Card. The search giant also announced that Visa, Discover and American Express have agreed to enable their cards to be added to future versions of Google Wallet.

Google Wallet was first unveiled in May bundled with coupon service Google Offers. The mobile payment app uses a technology called near field communication (NFC), which enables simple data to be transferred over a small distance between two devices with NFC chips planted.

Several tech bloggers gave Google Wallet a positive review, saying it is magical and impressive, but the impact remains to be seen as the NFC technology has not been widely adopted by customers and merchants in the United States.