The new rules, introduced last September, ensure customers can switch accounts within seven days with all outgoing and incoming payments automatically transferred.

They are part of a range of measures designed to break the dominance of Britain's four biggest banks - Lloyds Banking Group (>> Lloyds Banking Group PLC), Royal Bank of Scotland (>> Royal Bank of Scotland Group plc), Barclays (>> Barclays PLC) and HSBC (>> HSBC Holdings plc) - which between them control three-quarters of UK retail accounts.

Lawmakers and regulators believe a lack of choice has been a factor behind scandals such as the mis-selling of loan insurance and complex interest rate hedging products, which have cost banks over 20 billion pounds ($32 billion) in compensation.

The Payments Council said banks had met the seven-day deadline in 99.6 percent of cases, with 306,240 switches completed. A survey by the body, which has responsibility for ensuring payment services work in the UK, showed about six out of ten people were aware of the service.

"More than 300,000 switches in three months is an encouraging start and we hope this will be further boosted by the second wave of our national advertising campaign that kicked off this January," said the Payments Council's Chief Executive Adrian Kamellard.

The increase was more marked in December, when there was a 54 percent rise in customers moving accounts.

Britain's opposition Labour Party considers the government's efforts to heighten competition among banks to be inadequate and its leader Ed Miliband is expected to call for a cap to be introduced on the market share of individual banks in a keynote speech on Friday.

(Reporting by Matt Scuffham; Editing by Pravin Char)