David Cameron took on MPs to defend his father and his offshore fund in the House of Commons.
The prime minister argued the fund was set up to trade in dollar securities and "there are thousands of these investment funds".
The prime minister added: "The BBC, the Mirror Group, Guardian newspapers and to pick one council entirely at random, Islington Council, all have these sorts of overseas investments".
ITV News Political Editor Robert Peston reports:
Dennis Skinner was booted out after refusing to withdraw the comment he made to the Prime Minister in a debate over the tax row.
The Labour leader declared £1,850 in additional income, but was fined £100 for submitting his tax return a week late.
Chancellor George Osborne has released his tax return after the prime minister urged him to publish the records.