Reuters reports that the Wells Fargo trial is part of a major push by Visa to have a commercially-viable product ready for launch in 2011.

"We want to be commercially ready early in 2011" to let consumers use their cellphones to make purchases in stores, Bill Gadja, Visa's head of global mobile products told the newswire.

Wells Fargo joins Bank of America and US Bancorp as the third US bank to sign up for the field trials, which will run through to the end of the year.

The card giant is using DeviceFidelity's In2Pay Micro-SD chips which can be inserted into handset memory card slots, turning them into contactless payments devices.

In August, Visa announced that it is working with Turkey's Akbank to test the technology in Europe.

Visa is facing competition in US markets from telcos like AT&T and Verizon, who are partnering with Discover and Barclays to test NFC payments using technology from C-Sam and Gemalto.