Mr Miliband said: “Let’s take Stanley Fink who gave £3 million to the Conservative Party.
“He actually appointed him as Treasurer of the Tory Party and gave him a peerage for good measure. So now can he explain what steps he is going to take to find out about the tax avoidance activities of Lord Fink?
Lord Fink – who was chief executive of the hedge fund Man Group from 2000 to 2007 – is estimated to have donated £20million to charities over the past two decades.
But in a letter to Mr Miliband, he said the claims were “untrue and defamatory”, saying: “These are the facts: I was posted by the Man Group to run their office in Switzerland for four years from 1996 until 2000.
“During this time I had need of a local bank account to do simple things like receive my Swiss Franc salary and pay grocery bills.
“As I already banked with HSBC in London, I set up an account with HSBC. I subsequently set up an account with Credit Suisse as they had a branch much closer to my home and office.
“I submitted tax returns in both Switzerland and Britain showing my revised tax status, which was accepted by the Inland Revenue.
“I find it extraordinary that you have made claims against me that are without foundation or without contacting me.
“I challenge you to repeat your allegation outside the House of Commons – or to withdraw it publically.”
In two thirds of the HSBC accounts, no tax was due, probably because of the fact that the account holders were not domiciled in the UK for tax purposes.