Britain’s bailed-out banks are penalising first-time buyers by charging the biggest margins on loans with small deposits.

The Bank of England said last week that credit was becoming more easily available. However, those with small deposits largely remain frozen out.

Government-owned banks Halifax, Northern Rock and Royal Bank of Scotland (RBS) charge the largest premiums for first-time buyers, data provider moneyfacts.co.uk said.

In some cases, borrowers would be better off taking out a personal loan to fund a larger deposit.

Halifax is the worst offender according to Moneyfacts. If you have a 25% deposit, you can get a two-year fix at a rate of 4.29% with Halifax. If you have only 15% to put down, your rate is ramped up to 6.69% — a difference of 2.4 percentage points. On a £250,000 property, the customer with the smaller deposit will pay £10,565 more in interest for needing to borrow an additional £25,000.

In contrast, Skipton Building Society charges 4.99% and 5.99% for 25% and 15% deposits. The percentage point difference means the customer with the lower deposit pays only £6,548 more — almost 40% less than Halifax.

Michelle Slade at Moneyfacts said: “The nationalised lenders are taking the biggest margin for risk.”

At the same time, non-taxpayer owned banks are making moves to loosen their lending criteria.

From tomorrow, HSBC will allow borrowers with a 25% deposit to apply for its best-buy tracker — 2.95% with a £799 fee. Previously, only those with a 40% deposit could apply. Abbey, owned by Spanish bank Santander, has launched a new four-year fix at 5.84%, available to those with a 15% deposit. There is a £495 fee.

Meanwhile, brokers have received a flood of rejected mortgage applications from Abbey — many of them for first-time buyers — as it struggles with a backlog from its takeover of Alliance & Leicester.

Savills and London & Country said Abbey knocked back scores of applications last week, as its systems buckled.

Borrowers whose loans had been agreed — but where Abbey was awaiting further information — were among those rejected.

Abbey admitted there was a backlog due to increased business.