BIG-NAME mortgage lenders have been accused of employing underhand moves to boost their profit margins – raising their loan fees by as much as three times the level they were a year ago.

HSBC, Royal Bank of Scotland (RBS) and Abbey are among the worst offenders, according to financial data firm Defaqto, raising arrangement fees on some deals by 183%, 110% and 92% respectively since the start of the credit crunch a year ago.

Overall, lenders have raked in £3m in the past month by lifting fees on fixed-rate deals by an average £50, while grabbing headlines by cutting their loan rates.

They are also boosting their margins by failing to pass on the full reduction in the cost of wholesale funds, and charging more on unsecured personal loans.

Abbey’s average fee on fixed rates is the highest at £1,076.10 – up from £561.54 in August last year.

RBS now charges an average £868.23 on fixes, up from £413.50, while HSBC has a typical arrangement fee of £313.78 – almost three times the £111 charged a year ago.

The huge fee increases cancel out much of the benefit of the latest round of rate cuts. For example, Abbey – which overtook Halifax as the biggest lender in the first half of this year – has cut the rate on its three-year tracker from 5.89% to 5.79%, but raised the arrangement fee by more than 30% – from £1,499 to £1,950.

On a £200,000 loan, the changes result in a mere £9 cut in mortgage repayments to £1,275 a month, if fees are added on.

“Lenders are able to use arrangement fees as a hidden way of boosting the overall cost of the mortgage,” said David Black of Defaqto. “It’s worrying that some of the lenders taking the most business have introduced the biggest fee increases.”

Overall, the average arrangement fee on fixed-rate mortgages has fallen by 2.4% in the past year – to £854.12 from £874.30.

Of the lenders attracting the most business, however, only Nationwide’s fees have fallen. They are down 43% from an average £527 to £299.47.

The fee rises come amid a frenzy of mortgage-rate cuts in recent weeks, with lenders spurred on by sharp falls in wholesale borrowing costs.

However, lenders have failed to pass on the full reduction. Two-year swap rates – used to price fixed-rate mortgages – have dropped by 50 basis points in the past month, but the average rate on a two-year fix has fallen by not even 20 basis points from 6.96% to 6.79% – according to price-comparison website, Moneyfacts.

“Lenders are clearly still intent on improving margins: this situation is unlikely to change in the near future,” said Melanie Bien at independent broker Savills Private Finance.

Homeowners are not the only ones to suffer – lenders have raised rates on unsecured loans by an average of 2.6% since the last time Bank rate was at its current level of 5%, Defaqto said.

In December 2006, the average loan rate was 8.7% – 2.6 percentage points higher than the present average of 11.3%. The best-buy rate on a £5,000 loan now costs £277 more over four years.