Zapp has been set up by Vocalink, the group which runs Britain's payments infrastructure and is owned by a consortium of its biggest banks. It has already partnered with Europe's biggest bank HSBC, Santander, Britain's biggest customer-owned lender Nationwide and challenger Metro Bank.

"We are in varying degrees of discussions with the remaining banks in the UK and are confident of making more announcements in the next few months," Chief Executive Peter Keenan told Reuters at a media event in London on Thursday.

(Reporting by Matt Scuffham; Editing by Jemima Kelly)