Tesco PLC, the U.K.'s largest retailer, has agreed to use a core banking application from Fiserv Inc. in its retail banking unit.

Fiserv, of Brookfield, Wis., said Friday that Tesco Personal Finance PLC would implement its Signature processing platform as part of an effort to expand in the U.K. financial services market.

The banking unit has more than 6 million customers. Its main businesses are insurance, credit cards and personal loans, and it is working on new products and services "to extend its financial services business from a collection of successful financial products to that of a full service retail bank," Fiserv said.