British Prime Minister David Cameron published tax summaries Sunday in a bid to end a row over offshore funds held by his late father, but the documents instead raised new questions about a 200,000-pound (280,000 dollars) gift from his mother.
The release of Cameron's tax details was prompted by the huge data leak last week of the so-called Panama Papers.
Cameron received two payments of 100,000 pounds from his mother in 2011, according to the tax summaries, which cover his five years as prime minister and one year before he took office.
The gift potentially allows the family to legally avoid some 80,000 pounds in inheritance tax, which is not payable on property or funds below 325,000 pounds unless the person making the gift dies within seven years of the transfer.
British media said the disclosure of the gift - after Cameron earlier said he had inherited 300,000 from his father and sold shares in his father's offshore investment fund for 30,000 pounds - raised more questions about his finances and showed he was involved in a legal "tax dodge."
"The extraordinary move seems set to plunge David Cameron into further controversy," The Guardian said.
"Cameron now faces questions over whether his family took elaborate steps to minimise the amount of inheritance tax that would eventually be due on their estate," the newspaper said.
The Times said Cameron had revealed "hidden wealth," but it called the disclosure of his financial affairs "a historic moment that will transform British politics."
Popular tabloids The Daily Mail and The Daily Mirror both said the gifts involved a legal "tax dodge."
Cameron is expected to announce a tax investigation on Monday of British companies and individuals named in the Panama Papers.
On Saturday, in the latest of a series of brief statements on his links to the Panama Papers, he admitted that he was at fault for his widely criticized response.
"I know there are lessons to learn and I will learn them," he said, asking critics to "blame me" rather than his advisers and media team.
Hundreds of left-wing protesters gathered on Saturday near Downing Street, the prime minister's official residence in central London, with many calling for him to resign.
Cameron initially said his father's registration of offshore funds in tax havens through the Mossack Fonseca law firm, which was the source of the leak, was "a private matter."
He later made statements saying that he and his immediate family held no offshore assets and would not benefit from offshore holdings in the future.