HSBC, the bank that offered a “rescue” mortgage deal to help homeowners facing surging repayments, is hitting the same borrowers who take up the deal with arrangement fees of up to £9,999.

The bank's “rate-matcher” deal, introduced in February, offers borrowers a fixed mortgage at the same rate they were paying before remortgaging.

The offer was marketed as a way of helping hapless homeowners who would otherwise have faced increases of hundreds of pounds in monthly mortgage repayments when they came to the end of their existing fixed deal, because of significant rate rises since the credit crunch.

However, it has emerged that after an increase last Wednesday in the fees charged for taking out the deal, the maximum fee for a customer applying for a 4.79 per cent deal on a £250,000 mortgage - the lowest possible rate that HSBC will match for borrowers who are not existing customers - rose by 50 per cent, from £5,000 to £7,699.

For existing HSBC customers, who can take out bigger loans of up to £500,000, the maximum fee rises to £9,999.

The increase makes it the highest fee on the market for a loan of this size, according to Moneyfacts.co.uk, the price comparison service.

Fees for borrowers with smaller loans who take out a rate-matcher deal have also risen considerably. The charge is based on the amount lent, as well as the interest rate.

On a £120,000 deal fixed for two years at 4.94 per cent, the fee has more than tripled from £999 to £3,299. On a £190,000 loan fixed for two years at 5.19 per cent, the fee has gone up by seven times, from £599 to £4,299.

HSBC blamed the increasing cost of mortgage funding for its decision to raise fees on the deal, after it had decided to extend the offer for a further six weeks.

A spokesman said: “We had to choose between pulling the deal, increasing fees or making a loss. We believe we made the right decision.”

The findings emerged after the Chancellor condemned mortgage lenders that charge high fees and called on them to treat borrowers fairly.

HSBC said that it believes it is “still the most competitive two-year fixed-rate provider in the market”.

A spokesman added: “This fee is based on a worst-case scenario and doesn't bear any resemblance to what the majority of customers would pay.”

Money Central: the 10 worst property investments ever