UK's Cameron not set to benefit from offshore funds

* Cameron faces questions after Panama papers leak

* His father named in law firm's files

* Scandal comes at difficult time for government (Adds Osborne quote)

By Kylie MacLellan and William James

LONDON, April 6 (Reuters) - Prime Minister David Cameron, his wife and their children will not benefit in future from any offshore funds or trusts, a spokesman said on Wednesday as the British leader faced more questions over family tax affairs.

Cameron's late father, Ian, was among the tens of thousands of people named in leaked documents from Panama law firm Mossack Fonseca which showed how the world's rich and powerful are able to stash their wealth and avoid taxes.

After having at first described it as a private matter, Cameron's office said on Tuesday that he and his family did not benefit from any such funds at present. Cameron also said he did not own any shares or have any offshore funds.

But his failure to say whether he or his family would benefit in future only intensified media speculation, with the story splashed across many newspaper front pages on Wednesday.

"There are no offshore funds or trusts which the prime minister, Mrs Cameron or their children will benefit from in future," a spokesman for Cameron said on Wednesday.

Cameron has cast himself as a champion in the fight against tax evasion, particularly in British-linked territories such as the British Virgin Islands and Cayman Islands, but the opposition Labour Party has said the "Panama Papers" show the government has failed to tackle the issue.

Labour lawmaker Wes Streeting, a member of parliament's Treasury Select Committee, told BBC Radio the latest statement from Cameron's office was welcome but there were still questions about whether he benefited from offshore funds in the past.

"The question will be when our prime minister says he is serious about tackling it (tax evasion) ... are we absolutely certain he doesn't have a vested interest? And if he does have a vested interest, will he be up-front with us about it?" he said.

The Telegraph reported that Ian Cameron's fund moved its operations to Ireland (Other OTC: IRLD - news) in 2010, the year Cameron became prime minister, as the directors believed it was about to "come under more scrutiny".

Asked whether the prime minister considered Ireland an offshore jurisdiction, his office repeated that Cameron had made clear he had no shares in any company and no offshore funds.

"STEAMING PILE OF CASH"

The "Panama Papers" add to a difficult few weeks for Cameron in which one of his senior ministers resigned, his government was forced to drop a key element of its budget and he has faced accusations of failing to protect Britain's industrial sector after Tata Steel (BSE: TATASTEEL.BO - news) put its entire UK operations up for sale.

Anthony Wells, a director at pollsters YouGov (LSE: YOU.L - news) , said that while the Panama story may not be that damaging for Cameron, it has stopped his Conservatives focussing on their strengths ahead of local and regional elections next month.

It (Other OTC: ITGL - news) has also diverted government attention away from a June 23 referendum on Britain's membership of the European Union.

"People already think Cameron is very posh, very rich and very out of touch. I expect most of the public probably assume he's got some huge steaming pile of cash stored away somewhere," he said.

"The Conservative Party could be talking about something where they are strong, like crime or the economy, where it would help them win votes. Instead they're not, they're talking about something that's really bad for them where Labour have something to say."

The media interest has spread beyond Cameron, with finance minister and close ally George Osborne also asked on Wednesday whether he had any offshore funds. Osborne comes from a wealthy family, but was not named in any of the "Panama Papers".

"All of our interests as ministers and MPs (members of parliament) are declared," he said.

A source close to Osborne added: "George has no offshore interests, in shares or anything else." (Editing by Giles Elgood and Anna Willard)