David Cameron has insisted he does not have "anything to hide" about his financial affairs after revealing he and his wife sold shares worth more than £30,000 in an offshore tax haven fund set up by his late father.
The Prime Minister has faced intense pressure to detail his interests since the Panama Papers leaks included details of Blairmore Holdings - which used "bearer shares" to protect investors' privacy.
In an interview with ITV News, he insisted it was a "fundamental misconception" that it was set up to avoid tax, saying his father Ian was being "unfairly written about".
And he said that while his and Samantha's profit from the scheme was "subject to all the UK taxes in the normal ways" - it came to just below the threshold at which capital gains tax would have applied.
Number 10 said Mr and Mrs Cameron bought their holding in April 1997 for £12,497 and sold it in January 2010 for £31,500.
The annual personal allowance for an individual in 2009-10 was £10,100 - meaning jointly the profit was just outside the threshold.
Mr Cameron, who has been a prominent campaigner for increased tax transparency, also repeated his willingness to publish his own tax returns.
Downing Street later confirmed this will take place "as soon as possible".
When questions first emerged this week about the PM's tax affairs, Downing Street initially said it was a private matter before first clarifying Mr Cameron had no offshore funds and trusts and then making clear the family would not benefit in the future either.
Opposition MPs used the latest admission from Mr Cameron to criticise his reputation and handling of the issue, with Labour's John Mann suggesting the PM "has no choice but to resign".
Tax evasion is not just illegal it's immoral.People evading tax should be treated same as common thieves.This agreement helps us tackle them— George Osborne (@George_Osborne) October 29, 2014
Labour deputy Tom Watson suggested Mr Cameron should consider "voluntarily paying the money that, in his own words, should morally belong to the exchequer".
He also said the PM may have to resign although added it is "too early to tell".
Speaking to ITV, Mr Cameron said: "I paid income tax on the dividends, but there was a profit on it but it was less than the capital gains tax allowance, so I didn't pay capital gains tax, but it was subject to all the UK taxes in all the normal ways.
"So I want to be as clear as I can about the past, about the present, about the future, because frankly, I don't have anything to hide.
"I'm proud of my dad and what he did and the business he established and all the rest of it.
"I can't bear to see his name being dragged through the mud, as you can see, and for my own, I chose to take a different path from my father, grandfather and great-grandfather, who were all stockbrokers, and I've got nothing to hide in my arrangements and I'm very happy to answer questions about it."
Mr Cameron said it had been "a difficult few days" since the mass leak of records from Panamanian law firm Mossack Fonseca as he launched a staunch defence of his father.
He also said he was not able to "point to every source of every bit of the money" that his father left him when he died - which he said amounted to around £300,000.
Pressed on whether he benefited from any part of the estate that was based in Jersey, he said: " Dad's not around for me to ask the questions now. But he was a very hardworking man. He built up a business. He left his house to my brother. He left me some money, and left things to my brothers and sisters, too.
"And I think, you know, there's pretty good transparency about all of that. And as I've said, in the future I'm not benefiting from any Cameron family trust. At the moment I own no shares, no investments. I have savings."
For Labour, Mr Watson told Sky News: " He may have to resign over this but I think we need to know a lot more about what his financial arrangements have been, why it's taken three days for him to answer legitimate questions from journalists, why he didn't come clean when he heralded in the new age of transparency, and what other shareholdings does David Cameron have or has had since he was a Member of Parliament."
SNP economy spokesman Stewart Hosie said Mr Cameron has "played the public" over the issue, adding he must "come clean" on other tax-related issues.
He said: "The public will understandably now find it hard to trust the Prime Minister."