Borrowers coming to the end of fixed-rate mortgages could be better off staying with their existing lender rather than locking into another short-term deal, as rates and fees for new customers have risen so sharply.

The base rate was cut by a quarter-point this week to 5 per cent but new mortgage customers are unlikely to see much benefit. While a number of the biggest banks – Halifax, Nationwide and Woolwich – passed on the rate cut to existing borrowers, some simultaneously increased the cost of new fixed and tracker mortgages.

“Gone are the days new customers would be treated well at the expense of existing ones,” said Louise Cuming, head of mortgages at Moneysupermarket.com.

Many initial offer rates are now almost as expensive as lenders’ standard variable rates. Borrowers with small deposits may find they have to pay more than the best SVR. Traditionally, SVRs, which borrowers revert to when their initial deal expires, have been about two percentage points higher than discounted rates. They do not generally have set up or early repayment charges.

“Some standard variable rates are stacking up pretty well against shorter-term trackers,” said David Hollingworth at London & Country. “Improbably, people are considering whether they might suit.”

Nationwide has one of the most competitive SVRs of 6.49 per cent, following this week’s cut. Its best two-year fixed rate is only marginally lower, at 6.1 per cent, and this is only for borrowers with at least a 25 per cent deposit. Borrowers with deposits of 5 per cent would have to pay 6.8 per cent, a premium to the SVR.

Lenders are unable to offer better short-term rates as their own cost of borrowing remains at a significant premium to base rate. Alliance and Leicester, Nationwide and Woolwich increased new rates again this week and other providers have signalled they will do the same.

Hollingworth said: “We are going to have to wait a while longer before we know whether the interest rate cut will eventually improve new business rates.”

In the meantime, lenders are loading premiums on to riskier loans. Halifax last week introduced a new tiering structure that rewards borrowers with deposits of 25 per cent or more and penalises those with low deposits. Woolwich is reserving its best rates for borrowers with a maximum loan-to-value of 60 per cent, while Abbey is offering better rates below 80 per cent.

“It is fairly apparent that lenders are looking for good margins and sound borrowers,” said Jeremy McGivern, founder of property search agent, Mercury Homesearch.

Banks and building societies appear more willing to sacrifice margins on savings accounts as they try to attract new retail funds.

Most have yet to announce how much they will cut saving rates but experts predict rates on older and “core” accounts will come down, while some best-buy deals may not be reduced at all.

Among the few changes unveiled so far, National Savings & Investments and Egg cut some rates by the full quarter point. Kaupthing Edge, the Icelandic bank, said its instant access account would continue at 6.5 per cent.

“Just as mortgages have decoupled from base rates, so best-buy savings are becoming decoupled,” said Kevin Mountford, head of savings at Moneysupermarket.com. He said top savings deals were offering the biggest premium above base rate for a long time.

Rachel Thrussell, head of savings at Moneyfacts.co.uk, said now could be a good time to lock in to a fixed-rate deal. Six-month and one-year savings bonds are paying rates of up to about 6.75 per cent.