By Estelle Shirbon and Paul Sandle
LONDON (Reuters) - British Prime Minister David Cameron took the unusual step on Sunday of publishing his tax records to try to end days of questions about his personal wealth raised by the mention of his late father's offshore fund in the Panama Papers.
Cameron's initial reluctance to admit he had benefited from the fund caused a furor, compounding his problems when he faces a huge political fight to persuade Britons to vote to stay in the European Union in a June 23 referendum.
The EU issue has split his Conservative Party, while the government has also been going through a tough patch over a senior minister's resignation, a u-turn on welfare cuts and accusations it is failing to protect Britain's steel industry.
After saying on Saturday that could have handled the fallout from the Panama disclosures better, Cameron released a summary of his tax records for the past six years.
But any hope that would draw a line under the row was short-lived, as the main Sunday newspapers zeroed in on a gift of 200,000 pounds ($282,500) Cameron received from his mother in 2011, suggesting it may be a way of avoiding inheritance tax.
A source at Cameron's Downing Street office said the suggestion was inaccurate.
Cameron is one of dozens of politicians around the world who have been hit by the leak of 11.5 million documents from the Panamanian law firm Mossack Fonseca that detail the creation of more than 200,000 companies in offshore tax havens.
Cameron will make a statement about tax policy to parliament on Monday to try to regain the upper hand.
Labour Party leader Jeremy Corbyn has accused him of misleading the public by issuing what Corbyn described as four "weasel-worded" statements in as many days before finally admitting that he had benefited from his father's fund.
Some politicians campaigning for Britain to vote to stay in the EU in June's referendum are concerned that the damage to Cameron is bad for their side, as he had previously been considered the best advocate for an "In" vote.
"The scandals over David Cameron's finances ... may tip the decision further towards 'Leave'," said former Scottish National Party (SNP) leader Gordon Wilson on Sunday.
Nicola Sturgeon, SNP leader and first minister of Scotland's devolved government, published her latest tax return on Sunday, adding to pressure for greater transparency by politicians.
Cameron is not accused of having done anything illegal, and the fact that he is a wealthy man is nothing new.
But the past week has been damaging because the drip-drip of carefully worded statements before the fuller disclosure created the impression he may have had something to hide.
"He's not behaved improperly in any way and he's gone further than any prime minister previously in publishing these tax returns," Conservative minister Dominic Raab told Sky News television, accusing Cameron's Labour critics of "unsavory" personal attacks and comparing them to "hyenas".
Cameron announced a new taskforce on tax evasion would be led by the tax authority, HMRC, and the National Crime Agency.
The Guardian newspaper reported later that HMRC boss Edward Troup's former employer, London-based law firm Simmons and Simmons, had counted Cameron's father's fund among its clients.
The Guardian made no suggestion of wrongdoing by Troup or Simmons and Simmons. HMRC said Troup had never had any dealings with Mossack Fonseca or advised any of its clients named so far. It added that any HMRC officers with a potential conflict of interest would exclude themselves from a relevant investigation.
Bookmakers William Hill said they had cut their odds on Cameron resigning as prime minister this year to 2/1, compared with 16/1 when he won the last general election last May.
Cameron said on Thursday his father's investment trust was not set up to avoid tax but to invest in dollar-denominated shares. He said he had paid all taxes due on his own investment, which was worth about 30,000 pounds when he sold it in 2010.
But Cameron stands accused of hypocrisy after portraying his government as being in the forefront of global efforts to crack down on offshore tax havens. A comment he made in 2012 about a famous comedian's legal tax avoidance scheme being "morally wrong" has been widely quoted by media.
The documents disclosed by Downing Street on Sunday, from RNS Chartered Accountants, show Cameron paid tax of 75,898 pounds on income of 200,307 pounds in the 2014-2015 financial year, the most recent one included. ($1 = 0.7080 pounds)
(Additional reporting by Elisabeth O'Leary in Edinburgh; Editing by Ros Russell and Peter Cooney)