Britain's opposition Labour Party has promised major changes to the banking sector if it wins the next election.
Labour leader Ed Miliband said it was time for a reckoning with the banks,which did not lend enough to small businesses and overcharged for their services.
He said a Labour government would create two new lending institutions by getting the existing banks to sell off branches.
The big five banks - HSBC, Barclays, RBS, Santander and Lloyds Banking Group - account for the majority of bank customers and lending, the BBC reports.
Bank of England Governor Mark Carney earlier said that he supported the view that a cap on banks' market share "would not result in substantial improvement to competition".
But Mr Miliband said a Labour government would instruct the Competition and Markets Authority to report within six months of the May 2015 general election what the limit on a bank's market share should be and the timetable for any sell-off of branches, which should be completed by 2020.