Ed Miliband has fought back after Monaco-based Boots boss Stefano Pessina said Labour's policy platform would be a "catastrophe" for the country.
Answering questions from young people as part of Sky News' and Facebook's Ask The Leaders event, the Labour leader told his audience that "people won't take kindly to someone who avoids paying their taxes telling them how to vote".
"There's nothing that annoys people more than tax avoidance by big companies," he went on.
"Mr Pessina, who has been trying to lecture us about what we should do in this country, frankly I think he should be paying his taxes."
Asked if that meant he wanted to stop other big companies avoiding paying their taxes, Miliband replied: "Absolutely, we have got to deal with this."
This comes after Miliband's other Labour colleagues lashed out at Pessina, who has an estimated fortune of £7.5 billion. Shadow business secretary Chuka Umunna said voters would draw their own conclusions about business leaders who live abroad and do not pay tax in UK wading into British politics.
"It is important that the voice of business is heard during this general election campaign, not least on Europe," he said.
"But the British people and British businesses will draw their own conclusions when those who don't live here, don't pay tax in this country and lead firms that reportedly avoid making a fair contribution in what they pay purport to know what is in Britain's best interests."
Pessina, who oversaw the £46 million merger of Alliance Boots with American firm Walgreens and is now its acting chief executive, told the Sunday Telegraph: "If they acted as they speak it would be a catastrophe."
Shadow foreign secretary Douglas Alexander dismissed the attacks as "rubbish", while Lucy Powell, vice- chairwoman of the election campaign, rounded on critics within the party, warning they were "not helpful".
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Walgreens Boots Alliance insisted that Pessina's comments had been "taken out of context". A spokesman said: "The comments made by Stefano Pessina were a small part of a much larger conversation and have been taken out of context.
"As a businessman, international entrepreneur and investor, he takes a natural interest in a broad range of topics within the economic landscape of countries where he has business interests, like he has done previously in the UK, Europe and the USA.
"Stefano Pessina was expressing his personal views only and is not campaigning against Ed Miliband or the Labour Party."
Meanwhile, Ed Balls said he was expecting similar "rhetoric" from big figures. "In the next three months we are going to have a number of people brought forward by the Conservatives - whether it is Gary Barlow or Mr Pessina - saying 'Don't vote Labour'," he said.
"The idea that somebody who doesn't pay any tax in Britain should be telling British people how to vote, I think, will stick in the craw.
"The interesting thing about this company, even though Mr Pessina is a tax exile in Monaco, and even though he has moved the domicile of Boots to Switzerland, the only tangible thing he said in the Telegraph on Saturday was his fear is of Britain leaving the EU.
"That's what I hear from businesses up and down the country all the time."