The UK’s biggest high street banks have emerged as the chief winners from the Northern Rock crisis, as disgruntled former customers of the beleaguered bank seek a safe-haven for their cash.

Barclays, the UK’s third biggest bank, told The Times that it had seen an influx of millions of pounds in deposits since the run on Northern Rock, while Lloyds TSB and Abbey are also understood to have seen a surge in savings accounts being opened by disaffected former customers of the ex-building society.

Nationwide, the UK’s biggest building society, said that it had received sums approaching seven figures in deposits from new customers.

National Savings and Investments (NS&I), the Government-backed savings institution, has also reported a spike in the number of savings accounts opened after the run on the Northern Rock bank, with some individual deposits of up to £1 million. It said that the number of applications plateaued this weekend, but had remained at unusually high levels.

Despite a guarantee from the Bank of England that money held in Northern Rock deposits is safe, thousands of savers have taken the debacle as a cue to review where they keep their savings. Abbey has estimated that there is £57 billion up for grabs as investors move money to take advantage of market conditions.

A spokesperson for Barclays said: “We have seen a significant increase in the number of people opening savings accounts. Millions of pounds worth of savings deposits.”

Steve Cowdry, of Nationwide, said: “Some of our branches have seen a strong influx of funds from new customers in response to the situation with Northern Rock. Much more than we would normally expect.”

The deluge comes as high street banks, building societies and investment management companies are setting out their stalls to capitalise on investor insecurity following the credit crunch that led to the crisis at Northern Rock.

Fidelity, the fund manager, yesterday began targeting cash depositors with money market funds, offering 6 per cent interest. Richard Wastcoat, of Fidelity, said: “Money market funds should appeal to those savers who have been unsettled by the credit crunch. These funds spread a saver’s money across highly liquid cash-like securities.. and so provide some protection from the collapse or closure of a single financial house.”

However, savings experts warned that the well-known household name banks that are making millions from the Northern Rock fallout rarely offer the best value.

Sue Hannums, of AWD Chase de Vere, the independent financial adviser, said: “The problem is that a lot of the best rates are not offered by the well-known brand name banks. Savers might want peace of mind, but they are sacrificing good returns. The best accounts on the market from less mainstream banks offer up to 6.91 per cent, with a Birmingham Midshires 11-month bond, or 6.9 per cent on a one-year fixed rate from Anglo Irish Bank.

Barclays best savings account currently pays an interest rate of 5.39 per cent on an account with restrictions, while Abbey offers a maximum of 6.7 per cent on an e-Bond. NS&I offer rates on index-linked certificates for higher-rate taxpayers equivalent to 9.08 per cent tax-free and 6.3 per cent on their best-selling cash Isa, but offer poor rates on standard easy access accounts.

Anyone with money under the mattress was urged to deposit their money now, as the high rates seen over recent weeks are beginning to disappear from the market as a result of a recent fall in the LIBOR, the inter-bank lending rate.

Ms Hannums said: “At the moment, good rates are out there, but they won’t last forever. If your money is under the mattress, now is a good time to get it out.”