Opposition politicians demanded an investigation of tax havens on Tuesday after an offshore investment fund run by Prime Minister David Cameron's father was among several British companies listed in the Panama Papers.

Cameron's office said the use of Panama-based lawyers Mossack Fonseca as part of a tax avoidance scheme by Blairmore Holdings Inc was "a private matter." His father, Ian Cameron, controlled the fund from 1982 until his death in 2010.

Labour leader Jeremy Corbyn said it was "not a private matter if tax has not been paid," adding that leaked documents from the law firm had revealed tax avoidance on an "industrial scale."

"It's a private matter in so far as it's a privately held interest, but it's not a private matter if tax has not been paid," Corbyn told reporters.

"So an investigation must take place, an independent investigation," he said.

The listing of his father in some of the 11 million leaked documents also prompted calls by British media and politicians for Cameron to explain the current status of the Panama-registered fund, close loopholes in British tax law and even repay the tax avoided.

"The prime minister should lead by example and come out and set the record straight on his own tax affairs - we need full and total transparency," John McDonnell, Labour's shadow chancellor, said in a statement.

Cameron said he had no offshore assets to declare, but he did not say whether or not he or his family had benefited from tax avoidance schemes.

"I own no shares, no offshore trusts, no offshore funds, nothing like that," Cameron said when asked about his father's company during a visit to Birmingham.

"I would say that no government, no prime minister, has done more [than me] to make sure we crack down on tax evasion, on aggressive tax avoidance, on aggressive tax planning, both here in the UK and internationally," Cameron said.

He did not comment on the listing in the Panama Papers of several British entrepreneurs and former politicians who have made large donations to his ruling Conservative Party.

McDonnell said the Conservatives "should come clean and set out exactly what the situation is - is the prime minister happy to receive money from big donors who are accused of tax avoidance?"

The Daily Mail, one of Britain's most popular tabloid newspapers, said the naming of Cameron's father and the Conservative Party donors was embarrassing because Cameron has "spearheaded efforts to make international finance more transparent."

Steve Richards, a political commentator for The Independent, said Cameron "cannot be held responsible for his father's financial arrangements," but argued that the leaks reflect "the powerlessness of elected power."

"When the super-rich have the power to avoid their fair share of tax, the elected rulers become even more constrained," Richards wrote in the newspaper.

Ahead of a June referendum on whether Britain should remain part of the European Union, he said the leaks were "a vivid illustration of why going it alone is not a viable option for a medium-sized economic power."

The International Consortium of Investigative Journalists (ICIJ), which analysed documents first leaked to German daily Sueddeutsche Zeitung, quoted a Blairmore Holdings prospectus for investors as saying the investment fund should be managed "so that it does not become resident [in Britain] for taxation purposes."

The ICIJ quoted the leaked documents as saying the fund had achieved its offshore status by using untraceable "bearer shares" held by nominees in the Bahamas, a practice that Britain outlawed last year.

Latest news

Syrian opposition rules out future role for President al-Assad

The Syrian opposition said Friday it would not accept any role for President Bashar al-Assad in the future of the war-torn country, reacting to a recent US shift saying that removing al-Assad is no longer a priority for Washington.

Russian Army integrates breakaway forces of Georgian province

Parts of the small fighting forces of the Georgian breakaway province of South Ossetia have been placed under Russian military control, Russian Defence Minister Sergei Shoigu said on Friday.

Czech Republic's Pilsner Urquell beer is now Japanese

Japanese brewing company Asahi completed its takeover of the Czech brewery Pilsner Urquell on Friday, Asahi said in a statement.

Judge approves 25-million-dollar settlement of Trump University case

A US district judge on Friday approved a 25-million-dollar settlement of lawsuits and state fraud allegations against Trump University, the US president's now-defunct business venture.

Former Thai premier Thaksin to junta on reconciliation: 'Cut me out'

Former Thai prime minister Thaksin Shinawatra on Friday announced that he is not interested in the junta-led reconciliation process, three days after the junta handed him a half-a-billion-dollar tax bill for his past business deal.

Dalic: We welcome possible deal between Agrokor and banks

The government welcomes the possibility of an agreement being concluded between the Agrokor food company and creditor banks, and the bill on vitally important companies is not a fallback plan but the result of the government's care for the overall economic and financial stability of Croatia, Deputy Prime Minister and Minister of Economy Martina Dalic told a press conference in Zagreb on Friday.

Croatia, China sign action plan for cooperation in agriculture

The Croatian and Chinese ministries of agriculture on Friday signed an action plan for cooperation in the field of agriculture for the period 2017-2018, the Croatian ministry said in a statement.

ZSE indices up, Agrokor shares in focus of investor interest

The Zagreb Stock Exchange (ZSE) indices on Friday rose by more than 1.8%, with stocks of the Agrokor food and retail concern being in the focus of investor interest again.

Berlin police defend handling of Berlin market attacker

Berlin police defended themselves on Friday against accusations that they stopped surveillance on Berlin Christmas market attacker despite knowing in June 2016 he was dangerous.

Croatia, creditors tailor emergency measures to save tottering giant

Croatia's tottering retail and food giant Agrokor reached an agreement with its creditors, putting its debts standby and allowing it to continue working during emergency restructuring, the Croatian branch of Austria's Erste Bank said Friday.

Agrokor's creditors say standstill agreement to go into force today

A standstill agreement regarding the Agrokor concern's existing financial obligations to banks will take effect on Friday, additional capital will be injected into the concern in the coming days and the concern will be actively restructured, which includes a change of its management, it was said on Friday after a meeting between Agrokor's suppliers and creditor banks.

Palestinians, UN slam Israel's new settlement plan

Palestinians, Israeli activists and the UN lambasted the government of Israeli Prime Minister Benjamin Netanyahu on Friday, a day after it gave the go-ahead for the first new West Bank settlement in a quarter of a century.

South Sudan rebels release three abducted foreign oil workers

South Sudanese rebels have released three foreign engineers they abducted in early March in the oil-rich Upper Nile region, Foreign Affairs Ministry official Mawein Makol Arik said on Friday.

Turkish opposition: Imprisoned party chief has gone on hunger strike

The head of Turkey's pro-Kurdish opposition party has launched a hunger strike from prison.

European leagues threaten Champions League schedule clashes

The European Professional Football Leagues (EPFL) on Friday threatened schedule clashes on Champions League matchdays in an ongoing dispute with the governing body UEFA.

Danish court revokes citizenship of IS volunteer

A Danish appellate court on Friday stripped a man of his Danish citizenship for volunteering to fight for the extremist Islamic State in Syria.

Banks and Agrokor agree on key elements of standstill agreement

Member banks of the coordinating committee of financial creditors and representatives of the Agrokor food company have in principle agreed on key elements of a standstill agreement, which is expected to be signed later today, announcing changes in the company's management team, Erste Bank said in a statement on Friday afternoon.

Syrian man on trial in Sweden; mosque attack labelled terrorism

A Syrian man went on trial Friday in the southern Swedish city of Malmo, charged with terrorism and arson after an attack last year on a building used as an assembly hall by Shiite Muslims.