The Treasury is drawing up plans for a “Tell Sid” style campaign to boost household investment in shares, amid fears Britons are losing out by keeping cash in savings accounts which pay less than inflation each year.

Officials are understood to be considering proposals for an advertising blitz encouraging consumers to take their money out of bank accounts and put it in the stock market.

It comes after the Government criticised big banks for leaving their savers stuck with ultralow interest rates while dramatically increasing costs for mortgage borrowers.

Executives from NatWest, HSBC, LLoyds and Barclays are being hauled in to a meeting with the Financial Conduct Authority on Thursday to explain the growing gulf.