In the bank's interim results for the first six months of the year released this morning, it said that total lending to small businesses had fallen by £400m.

Sidney Bobb, chairman of the BAPC, said that small businesses were being punished for a problem that was not of their making.

"It is not small businesses that have created this problem – a small printer with his £10,000 overdraft is not responsible for the credit crunch," he said. "At a time when the economy needs a kick start more than ever, businesses need access to funds to grow and invest in equipment."

Meanwhile, one printer, an RBS customer, said: "You couldn't print what I think about this."

However, RBS said that the reason for the shrinking of the loan book was the customers were deleveraging their balance sheets and paying off debt, rather than borrowing more.

It claimed that 85% of small businesses that applied for a loan were sucessful over the six-month period.

John Wright, national chairman of the Federation of Small Businesses, said: "Figures from the British Bankers Association indicate that more firms are dipping into their savings, which shows that many small businesses might be put off from going through a torturous application procedure for a loan or overdraft extension, which ultimately might not be successful."

He added that RBS and other high street banks must ease up on finance to viable small firms and go back to trusted ‘relationship banking’ with their small business customers.

The figures came as the RBS announced a pre-tax profit of £15m, but warned that it had not yet seen the peak of its write offs, which reached £7.5bn in the six-month period.

In addition, the bank said that after paying tax and dividends to the government, the total loss for the period was almost £1bn.

RBS is the last bank to unveil its results in a week of interims from the UK's banks, which saw tens of billions of pounds of writedowns on bad debts.