Web giant Google has merged its online payments service Checkout with mobile payments system Google Wallet.

The switch will require no changes for merchants, the company said, and Checkout users will be able to transition their account to Google Wallet the next time they sign in.

Google also announced a new integration option for Google Wallet, that it claims will online merchants to optimise payments for the mobile web. "When consumers visit […] sites from an Android phone, BlackBerry or iPhone, they will have the option to make a purchase using Google Wallet, without the need to fill out multiple forms or leave the merchant’s site."

The mobile payments component of Google Wallet is based on Mastercards’ PayPass contactless payment infrastructure. So far only US stores have signed up directly, although pre-paid Google Wallet cards can be used at any store that supports Paypass, which includes Tesco and Boots in the UK.

Yesterday, fashion retailer Gap announced that it will support Google Wallet payments in 65 of its stores in California’s Bay Area. Gap said that it will be using the platform not only to transact payments from customers’ smartphones, but also to offer discounts.

"Starting today through the end of February, Gap will offer 15% off your entire purchase when you use Google Wallet to shop at our Bay Area stores," Gap’s business development director Nick Sheth wrote on the company’s blog.