BANKS and building societies will net an extra £52m over the next year by manipulating current-account rates.

Overdraft rates have gone up by far more than Bank rate, while current-account customers who stay in the black have seen rates go up less, according to a survey by comparison firm Uswitch.

While Bank rate is up by 0.5 percentage points since January, the nine banks in the survey have increased authorised overdraft rates by an average 0.93 points.

Meanwhile, rates if you are in credit have gone up by a miserly 0.02 points.

It is estimated that about 25m bank consumers who use their authorised overdraft facility will be affected by the rate hikes.

This research emerges at a time when the furore surrounding bank charges has hit new levels, with campaigners accusing banks of blackmailing customers to deter them from reclaiming penalties. The OFT is already probing unfair bank charges and will report later in the year.

The worst offender is Halifax, which has upped its overdraft rate by two points and cut the in-credit rate by one point on its flagship current account. HSBC has increased overdraft rates by two points.

Lloyds TSB, Britain’s largest current-account provider, has increased its authorised overdraft rates by up to 0.25 points this year, but over nine months it has hiked them by up to 3.1 points, from an average of 14.8% to 16.1%. Bank rate increased by only 0.75 points in that time.

Over the same period Lloyds has increased its in-credit interest rates by an average of just 0.12 points.

Lloyds is expected to generate an extra £23m in the next year through this rate squeeze because about 2.72m of its customers are regularly overdrawn, according to Mike Naylor at Uswitch.

He said: “These banks have been sneaky by just increasing overdraft rates and not the in-credit rates and we are pretty certain that the other banks will follow this trend by the end of the year.”

Naylor suggests customers who use their overdrafts often should move to Alliance & Leicester’s Premier Direct current account, which offers a 0% introductory rate on its overdraft for 12 months, reverting to just 5.9%.

In a separate survey, Moneysupermarket, another comparison firm, looked at how bills would stack up if a customer was overdrawn by £60. It found a huge variation. HSBC would charge only £25 while Halifax, NatWest and A&L would all impose fees of more than £100. NatWest was the most expensive at £133 – some 432% more than HSBC, and more than double the unauthorised amount borrowed.