Ed Miliband has pledged not to “back down” in his campaign on tax avoidance, and accused David Cameron of “turning a blind eye” to the benefit of the rich and powerful.
The Labour leader insisted he would govern “without fear or favour” after a week of bitter political wrangling on the issue.
In a speech to the Welsh Labour conference in Swansea, he said: “It doesn’t matter how much I get attacked for this, I’m not backing down.
“I will stand up to all those who stand in the way of success for working families.
“A Labour government led by me will ensure that the same rules apply to everyone, not matter how rich or how powerful they are.”
Mr Miliband has faced questions about his own tax affairs, with allegations that split ownership of his parents’ former home after his father’s death was used to cut inheritance tax liabilities.
He also drew attention to his clashes with Boots boss Stefano Pessina and Tory donor Lord Fink, in a battle he judges is popular with voters.
“Two weeks ago, the British people were being told how to vote by a billionaire who doesn’t even pay tax in the United Kingdom and has moved the HQ of his company, Boots, from Nottingham to Switzerland,” he said.
“Last weekend I promised the next Labour government would tackle the scourge of tax avoidance, setting a six-month deadline for tax havens operating in UK Overseas Territories and Crown Dependencies to open up their books or face being blacklisted.
“This week, there were a series of revelations over industrial scale tax avoidance at HSBC in Switzerland which this government had known about even when it appointed its chairman as a trade minister.
“And then just on Thursday the man appointed to be Treasurer of the Conservative Party first threatened to sue me for saying he was a tax avoider then announced that ‘everyone is a tax avoider’ and he was just guilty of ‘vanilla tax avoidance’.
“As always, this becomes a story of Westminster games: who’s up, who’s down, political knockabout. But in fact, this isn’t really about Lord Fink, Stefano Pessina, David Cameron or me. It is about something bigger and deeper about our economy, our society and kind of country we want to live in.”
Mr Miliband also outlined plans for fresh penalties and new means of closing tax avoidance loopholes.
A Conservative spokesman said: “The culture and practices of HMRC went wrong under Labour – when top bankers paid lower tax rates than their cleaners, foreigners didn’t pay capital gains tax and the richest people routinely avoided paying stamp duty.
“It’s David Cameron who has been clearing up Labour’s mess – investing in HMRC to increase the number of prosecutions of tax dodgers, putting reform of the way multinational companies are taxed at the top of the G8 agenda and closing loopholes that the richest were exploiting under Labour.”