Current account customers are predicted to use their mobile devices more than internet, branch and telephone banking combined by 2020, according to a report released on Monday by Britain's banking lobby group.

British bank customers were already logging on via mobile devices 73.8 million times a week by the end of March, up from 18.6 million times a year earlier and 9.1 million times in 2013, said the report by the British Bankers' Association (BBA) and consultancy firm EY.

Branches continue to be displaced and there was a 6 reduction in branch transactions across all banks last year compared with 2013, the report said. Some banks have said branch transactions were falling by 10 percent or more.

The industry shift is prompting lenders to close more branches and devote increasing resources to mobile banking technology.

"The British public is voting with its thumbs. Being mobile-enabled is a must, not a maybe, and banks that don’t engage properly with mobile channels risk losing relevance in customer's lives," said David Ebstein, head of digital for financial services at EY.

British customers had downloaded 22.9 million mobile apps at the end of March, up from 14.7 million a year earlier, and customers moved 2.9 billion pounds a week using the apps in March, up 42 percent from 2014 levels, said the annual report.

Banks have said that customers are increasingly checking balances on mobile devices. Royal Bank of Scotland (>> Royal Bank of Scotland Group plc) said it had a record 4.9 million log-ins on one day alone and Barclays (>> Barclays PLC) said its app now handles 1,980 log-ins a minute.

The BBA report said that customers were logging on to the internet 66.9 million times a week by the end of March, up 10 percent year on year. 

(Reporting by Steve Slater; Editing by David Goodman)