Midlands businesses have lost millions of pounds because of a widespread bank “mis-selling” scandal.

MPs have condemned “Del Boy” selling techniques by banks which pressured firms into taking out complicated financial products known as interest rate swaps.

Companies were told the deals would protect them from soaring interest rates – but instead they lost money when interest rates hit record lows – and it has cost two firms in the West Midlands alone a total of £14.2 million.

Regulator the Financial Services Authority has already begun an inquiry, and has interviewed more than 100 small businesses to try to work out what exactly banks have been telling customers.

The true scale of the problem could be massive, with potentially thousands of firms affected.

But MPs queued up to condemn the banks as they highlighted the misery and hardship mis-selling has caused for businesses.

Victims include Guardian Care Homes, a Wolverhampton-based businesses which employs 900 staff in 30 care homes across the country – and stands to lose £12 million.

One Staffordshire businessman could lose his home as a result of the scandal, MPs said.

And a small business in Warwickshire firm has lost up to £200,000 after giving in to “high-pressure sales tactics” from its bank.

MPs raised the cases in the House of Commons, but warned that many other businesses were scared to come forward in case their banks took revenge on them for speaking out.

MP Mark Garnier (Con Wyre Forst) said the affair could come to be seen as “yet another large mis-selling scandal”, following the mis-selling of payment protection insurance (PPI) to hundreds of thousands of bank customers.

Banks least year paid out £2 billion in compensation to customers who had been mis-sold PPI.

MP Emma Reynolds (Lab Wolverhampton North East) said: “I think it is utterly disgusting that this is happening” and called on ministers to intervene, saying “Something needs to be done about this urgently”.

And describing the way one Warwickshire firm was treated, Marcus Jones (Con Nuneaton) said: “The capital arm of the bank pitched the product in what I can only describe as a Del Boy-esque fashion – as if Del Boy was selling saucepans to a housewife at the market.”

Interest rate swap products guarantee that the interest charged on a loan will not rise above a set level or fall below a set level. The bulk of the products were sold, alongside loans, to businesses between 2005 and 2008 – when rates were much higher than today.

MPs claim that businesses bought them in the belief they were simply safeguarding themselves against dramatic increases in interest rates.

But banks failed to explain that the products amounted to a gamble, in which the buyer stood to gain if interest rates rose significantly while the banks gained if they fell.

The Bank of England has held interest rates at an historic low of 0.5 per cent for 40 months running, which means that firms who took out interest rate swaps have lost out.

A preliminary inquiry by the Financial Services Authority in March concluded there was cause for concern about some of the sales practices involved, and about whether the products were ever suitable for smaller businesses.

Guardian Care Homes was sold two interest rate swap products in 2007, which were taken out against existing loans. But while it was told the products would protect it against the threat of interest rate rises, they actually cost the firm £12 million after interest rates plummeted.