Bank of England governor Sir Mervyn King has launched a stinging attack on British banks and called for a "real change in culture" as lenders became further embroiled in controversy.

Sir Mervyn said there was no need for a Leveson-style inquiry, but admitted "something went very wrong with the UK banking industry and we need to put it right".

The governor's comments came as a fresh mis-selling scandal involving complex financial products added to the anger surrounding the rate-rigging affair uncovered at Barclays earlier in the week.

Taxpayer-backed Royal Bank of Scotland also confirmed it was being investigated for manipulating the rates at which banks lend to each other, known as Libor.

Sir Mervyn said: "From excessive levels of compensation, to shoddy treatment of customers, to a deceitful manipulation of one of the most important interest rates and now news of yet another mis-selling scandal we can see we need a real change in the culture of the industry."

He added that hard-working bank staff have been "let down" and that banks now needed "leadership of an unusually high order".

The Financial Services Authority (FSA) revealed earlier that Barclays, HSBC, Royal Bank of Scotland and Lloyds Banking Group had agreed to pay compensation to customers who were mis-sold interest-rate hedging products.

Some 28,000 of the products have been sold since 2001 and may have been offered as protection - or to act as a hedge - against a rise in interest rates without the customer fully grasping the downside risks.

Martin Wheatley, managing director of the FSA's conduct business unit, said: "For many small businesses this has been a difficult and distressing experience with many people's livelihoods affected."

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The findings come after Barclays was fined £290 million by UK and US regulators for manipulating the rate at which banks lend to each other, and echoes the costly payment protection insurance (PPI) mis-selling scandal that emerged last year.

Banks are facing the threat of a criminal investigation over fixing the interbank lending figures that affect millions of homeowners and small firms.

The Treasury has started to look at strengthening criminal sanctions for those responsible for market abuse after the FSA exposed the dealings at Barclays on Wednesday.

Serious Fraud Office investigators are in talks with the regulator over the scandal, while pressure is mounting on Barclays chief executive Bob Diamond to stand down.

Prime Minister David Cameron said it was very important that accountability for what went on "goes all the way to the top of that organisation" and that Mr Diamond had "some serious questions to answer".