Labour has pledged to carry out a wide-ranging review of tax planning schemes if the party wins May's General Election.
Shadow Chancellor Ed Balls has also dismissed claims his party was involved in tax dodging.
It came as the Conservatives accused Labour of "breathtaking" double standards amid allegations property tycoon Sir David Garrard, who recently donated money to Scottish Labour, had an offshore trust that can be used in order to reduce tax.
There is no suggestion that Sir David did anything wrong.
Labour sources hit back suggesting that David Cameron was on the side of rich financiers and leading the "political wing of the hedge fund industry".
Meanwhile, the Liberal Democrat Business Secretary Vince Cable announced that he had written to the Chancellor George Osborne to ask why tax inspectors had prosecuted just one individual as a result of leaked documents of alleged tax dodging at HSBC's Swiss arm.
And in an unexpected move HSBC itself made a public statement offering its "sincerest apologies".
The row over party donors engulfed Westminster earlier this week amid allegations as many as seven Tory funders held Swiss accounts with HSBC.
Within an hour Mr Miliband had accused David Cameron of being a "dodgy" Prime Minister.
There was further controversy when one of those donors Conservative donors, Lord Fink, later suggested that "everyone" is involved ni tax avoidance.
Mr Balls admitted that a donation to Labour from millionaire businessman John Mills, had been "tax efficient".
He said that he would order a wide-scale review of tax-planning if he became Chancellor in May, the scope of which would include the use of 'deeds of variation' used by the Labour leader Ed Miliband on his family home.
Mr Balls said: "We will look at every area of tax law."
However, he said, there were differences between types of tax planning "We have ways in which people can sensibly plan for their children and for their death and the inheritance.
"But if people are actually setting up false structures to avoid paying tax or going off to live in Switzerland in [order] to avoid paying their fair share of tax, we will crack down in a way the Tories have completely failed."
He dismissed allegations that Labour had taken part in tax-dodging, although he suggest that a £1.6 million donation of shares, rather than cash, from Mr Mills had been "tax efficient" for the party.
"You can try and say 'did Labour get involved in a tax-efficient donation?'; I'm afraid, you know, it's small beer compared to what the Tories got up to."
And he reiterated his accusation that David Cameron was guilty of "turning a blind eye" to tax abuse abuses by rich individuals.
Yesterday, Work and Pensions Secretary Iain Duncan Smith claimed that the Uk's political funding system was "one of the cleanest in the western world".
But his Tory colleague Ken Clarke called on his party to be less reliant on rich benefactors.
Meanwhile, Mr Cable increased the pressure on Conservative ministers with a letter to the Chancellor demanding answers about the lack of prosecutions.
He said that the figures was "extraordinary" adding: "The contrast is that there are thousands of small tradesmen who are being fined by Inland Revenue often for small failures in VAT declarations.
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