Prime Minister David Cameron has branded comedian Jimmy Carr "morally wrong" for seeking to avoid taxes.
Media reports of Carr's tax arrangements suggest he is undertaking "straightforward tax avoidance", said the Prime Minister.
And he said it was unfair on the people who pay to watch the comic perform that he is not paying his taxes in the same way that they do.
Speaking to ITV News during a round of TV interviews during his trip to Mexico, the PM said: "I think some of these schemes - and I think particularly of the Jimmy Carr scheme - I have had time to read about and I just think this is completely wrong.
"People work hard, they pay their taxes, they save up to go to one of his shows. They buy the tickets. He is taking the money from those tickets and he, as far as I can see, is putting all of that into some very dodgy tax avoiding schemes.
"That is wrong. There is nothing wrong with people planning their tax affairs to invest in their pension and plan for their retirement - that sort of tax management is fine.
"But some of these schemes we have seen are quite frankly morally wrong.
"The Government is acting by looking at a general anti-avoidance law but we do need to make progress on this.
"It is not fair on hard working people who do the right thing and pay their taxes to see these sorts of scams taking place."
Carr is said to have used an aggressive - but legal - tax-avoidance scheme which enables members to pay income tax rates as low as 1%.