Google will offer mobile payments with MasterCard and Citibank, according to one of the people, as well as with cellphone carriers, hardware manufacturers and retailers. 

Initially, the mobile wallets will be available only on Google’s Nexus S phone and will use a Citibank-issued MasterCard credit card number and a virtual Google MasterCard prepaid card. Consumers will be able to make payments at any of the 124,000 merchants that have MasterCard’s PayPass terminals, which accept contactless payments, a person briefed on the deal said.