Part-nationalised Royal Bank of Scotland last Friday swung to a half-year loss as it took a £733 million hit on its exposure to Greece’s debt-laden economy.

The 83 per cent state-owned bank reported a loss of £794 million in the six months to June 30, compared with a £1.1 billion profit last year.

RBS was pushed into the red by the Greek write-off and an £850 million provision to cover compensation for customers who were mis-sold payment protection insurance (PPI).

Elsewhere, the British Bankers Association said Britain’s top five banks were on track to meet business lending commitments drawn up under the Project Merlin agreement with the government.

RBS, Lloyds, HSBC, Barclays and Santander UK have provided £100.4 billion in gross new lending in the first half of the year, including £37.4 billion to small businesses. The banks are committed to providing £190 billion of gross new lending this year, including £76 billion for small businesses.

Speaking to BBC Radio 4’s Today programme, RBS chief executive Stephen Hester said the bank’s restructuring was “going well”, adding: “We are getting risk down, the bad assets - that have been dogging us from past years – are coming down and I feel comfortable with the way that part of the RBS plan is unfolding.”

He said ongoing problems in world banking created “head winds which will affect us in different ways”, including writing down RBS’s exposure to Greek debt.

He believed the turmoil on the markets over the last 24 hours, showed the 2008 financial disaster was “not a banking crisis” but “one of global economic imbalances”.