Lenders are being accused of using the credit crunch to sneakily shift more borrowers on to standard variable rates which they can manipulate at will.

Moneyfacts , the financial-data provider, predicted last week that at least half of all borrowers will be on an SVR by the end of the year. Unlike trackers, which automatically follow Bank rate, lenders have complete discretion over when they move SVRs — and by how much — meaning borrowers can lose out.

Halifax and Nationwide raised rates on two-year fixes by as much as 0.5 points last week — borrowers with a 25% deposit will now pay almost 7% for Halifax’s two-year fix, with monthly repayments on a £200,000 loan at £1,412. Its standard variable rate is also 7%, so many customers will be tempted to go on to that and avoid Halifax’s £1,499 fee.

Most lenders now have two-year deals above their SVRs after the average two-year fix hit a 10-year high of 6.75%.

Nationwide has five two-year deals above the SVR of 6.49%, while Woolwich, which has an SVR of 7.14%, has one more expensive fix.

Darren Cook of Moneyfacts said: “If the current economic climate persists we may see more borrowers on their lender’s SVR than on an actual mortgage deal.

“The problem is that once you are on the SVR the lender can manipulate it at will. This is different to base-rate trackers which lenders are compelled to reduce in line with cuts to Bank rate.”

About 11% of UK borrowers are on a standard variable rate or discounted mortgage, linked to the SVR, representing about £118 billion in loans.

Although the Bank of England has cut interest rates three times since December, lenders have held out on cutting their SVRs — the average has fallen just 0.29 points in the past year, while Bank rate fell from 5.5% to 5% now — earning them an additional £247 million in interest.

Cook said: “This is unacceptable. Lenders are punishing homeowners at a time when families are feeling the pinch from rising household costs.”

While some lenders have closed their SVRs to new customers, homeowners coming up to remortgage may increasingly have little choice but to go on their lender’s SVR.

Dickon Edwards, 35, a barrister from Tottenham, north London, had no choice when he bought his new home.