Britain is facing a 'tsunami' of house repossessions as soon as interest rates start to rise, one of the country's leading bankers has warned.

Richard Banks, the chief executive of UK Asset Resolution (UKAR), the body that runs the £80bn of mortgages bailed out by the taxpayer during the banking crisis, also said in an interview with the Guardian that the Labour government's pleas at the start of the crisis for lenders to keep families in their homes was forcing some homeowners further into debt.

In a warning that the industry may have been too lenient with some of its customers, he said he believed a policy of "tough love" would be fairer to people facing long-term difficulty in keeping up payments on loans taken out when house prices were at their peak and personal incomes on the rise.

His warning came the day after the international bank regulator said the Bank of England, which has kept rates at 0.5% for more than two years, would have to raise rates shortly to curb inflation.

The Bank of International Settlements said the policy of the Bank of England, whose rate-setting committee is split over whether or not to increase borrowing costs, was "unsustainable".

With 750,000 customers, UK Asset Resolution, set up to run the nationalised mortgages of Bradford & Bingley and parts of Northern Rock, is the country's fifth largest mortgage lender. But 23,000 of those mortgage holders are more than six months behind with payments and Banks admitted the projections for the number of people falling behind on payments could get "scary" if lenders did nothing to prepare for higher rates.

"You can see if you don't do something about it, you can see a tsunami," he said. "If you don't get into the hills you could get drowned by this. If you don't manage this properly it could get very messy."

He regards it is an industry-wide problem, albeit one that might be concentrated at UKAR as its customers include buy-to-let landlords and so-called self-certified borrowers – those without salaried income. UKAR, through three calls centres in Crossflatts, West Yorkshire, Gosforth, Newcastle, and Doxford, Sunderland, has begun cold-calling customers it believes are at risk of falling behind on payments in an attempt to keep their mortgage payments on schedule.

The bank is also trying to tackle customers behind with payments for six months or more and at risk of repossession.

His concern about a surge in repossessions is partly the result of moves by the industry early in the 2008 crisis to grant so-called forbearance to help customers stay in homes by, for example, reducing monthly interest payments. "We as an industry, as a kneejerk reaction in the emergence of the crisis, and because the government asked us to be forbearing to customers in the hope it would all go away, we have been too lenient with some customers.

"It's a tough love approach," he said. "It's treating customers fairly, not nicely, because if you can't afford your mortgage you are only increasing your indebtedness. If we allow you to increase your indebtedness, that's not really fair to you."

This month the Council of Mortgage Lenders forecast a rise in repossessions from 40,000 this year to 45,000 next. This figure would still remain well below the 75,500 peak of 1991. The remarks by Banks follow a warning last week from the new regulator set up to spot financial risks in the system – the Financial Policy Committee (FPC) inside the Bank of England – that warned banks may be providing a "misleading picture of their financial health" if they were not making big enough provisions for borrowers in difficulty.

Forbearance has been brought into play in up to 12% of mortgages, the FPC said.

It also noted that the most "vulnerable" households were concentrated in a few banks. It did not scrutinise UKAR but noted that the two other bailed-out banks, Lloyds Banking Group and Royal Bank of Scotland, had the largest exposure to customers whose mortgages were bigger than their value of their homes.

Last month, the Financial Services Authority issued a guide to handling forbearance in which it warned: "Arrears and forbearance support provided with due care by firms has a beneficial impact for both the firm and the customer … However, where such support is provided without due care or any knowledge or understanding of the impacts, it has potentially adverse implications for the customer, for the firm's understanding of the risks inherent within its lending book, and in turn for the regulators and the market."