David Cameron is coming under increased pressure to disclose his affairs regarding Panama Papers leaks.
The documents that were released earlier in the week raise questions about the finances of dozens of world leaders, celebrities and sports stars, linked to off-shore tax saving schemes.
Dawn Butler, Christian Labour MP for Brent Central, told Premier's News Hour the public need more information.
She said: "Essentially for me, before I would say the prime minister needs to resign, or even if the prime minister wanted to resign, I'd want to know the rest of the information, what else is there that he hasn't told us.
"That's the main issue."
David Cameron said that he paid income tax on dividends but the £19,000 profit on the sale was insufficient to attract capital gains tax.
The PM also repeated his willingness to publish his tax return - and make it the norm for premiers and Opposition leaders, saying: "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," he told ITV News.
However, he also conceded that he was not able to "point to every source of every bit of the money" that his father left him when he died - around £300,000 - when asked whether it was linked to investments in Jersey.
Dawn Butler told the News Hour: "He benefitted from these offshore accounts and he had some shares.
"I think he had these shares since 1997, and he sold them in 2010, because he would have been advised by his special advisors - you cannot have these shares as prime minister, because it's morally wrong - probably is what they told him.
"So he sold the shares in 2010 - he says for a profit for £19,000 - now that's below, I think £500 or £1,000 just below the amount he would have had to pay capital gains tax on.
"So there's so many questions to answer in terms of how did he sell those shares, was it to a friend, is it still kept in the family?
"I just think it's all very murky at the moment."
However, opposition politicians said that Mr Cameron had given the clear impression he had something to hide by only revealing his involvement after days of pressure and a string of statements that failed to mention past investments.
They are pushing for the PM to come to the Commons on Monday to answer questions about the leak of millions of documents from Panama law firm Mossack Fonseca, which have linked many senior politicians to offshore schemes.
Dawn Butler finished: "We know that it's not illegal, that why it's a loophole.
"If you've got lots of money and really clever accountants you can get away with it because it's a loophole - and it's a loophole that as a ordinary person we wouldn't be able to do or use because we don't understand how it actually works, the intricies or how it works."
Listen to Premier's Antony Bushfield speak to Dawn Butler here:
