Mortgage lenders have been accused of keeping loan rates unfairly high, despite falls in their own cost of borrowing.
Last December the Bank of England decided to cut the base rate by a quarter point to 5.5 per cent. Most economists predict a further cut when the Bank�s Monetary Policy Committee meets tomorrow.
While leading lenders Halifax and Nationwide passed on December�s reduction in full to customers on standard variable rates (SVRs), others did not.
The Council of Mortgage Lenders (CML) said last month high Libor rates - the rate banks lend to one another at - were contributing to continued higher borrowing costs for homeowners.
But Libor rates have been steadily decreasing, from 6.71 per cent in December to 5.57 per cent yesterday. "This would indicate that there is now less reason for lenders to withhold decreases to their SVRs, with interbank lending rates no longer as significant," said Jonathan Cornell at Hamptons Mortgages.
"A base rate cut is designed to improve consumer confidence - but if banks yet again make the decision not to pass on the cut, they are likely to be met with much resentment."
About 45 per cent of homeowners are on either variable rates, which are set by the lender, or tracker rates, which are directly linked to base rate plus a specific margin - say, 0.5 per cent. Borrowers on a fixed-rate mortgage will not be affected by any rate fluctuations.
Although borrowers on a tracker rate should see their monthly repayments falling as the base rate falls, many banks and building societies have raised the margins on tracker mortgages in recent weeks. For example, a deal which had previously been available at base rate plus 0.79 per cent � which would equal 6.29 per cent � is now priced at base rate plus 1.19 per cent, or 6.69 per cent.
On a typical £100,000 mortgage, this would increase monthly repayments by about £25.
"With many lenders increasing their margins on tracker mortgages, this may dampen the recent surge in popularity for variable rate and tracker mortgages and instead signal a role reversal in the number of people now choosing to opt for fixed-rate deals," added Cornell.
Experts say that homeowners are being squeezed tighter than usual by banks because of the credit crunch.
"Banks have gone through a very expensive time of borrowing and they lost a lot of money at the end of last year," says Katie Tucker at broker John Charcol. "It�s the same across all lenders � they just can�t afford to be competitive at the moment."
