A leak of confidential files has apparently revealed how the rich and powerful hide their money in offshore tax havens.
More than 100 politicians and public figures have been named in millions of records obtained from a law firm in Panama.
Here is what we know so far.
What do the 'Panama papers' show?
Around 11 million files from the Mossack Fonseca law firm allegedly show how they helped clients launder money, dodge sanctions and evade tax.
Some 72 current or former heads of state implicated, including dictators accused of looting their own countries.
Prime Minister David Cameron's late father was among clients - including six peers, three ex-Tory MPs and political party donors - named in relation to investments set up by Mossack Fonseca.
As well as politicians and celebrities, drug dealers and Mafia members are also involved.
Who faces allegations?
A suspected $2 billion (£1.4m) money laundering ring run by a Russian bank - and said to involve close associates of President Vladimir Putin - is among the reported disclosures.
The Kremlin has said claims implicating Putin are baseless and only published to discredit him.
Syrian president Bashar al Assad, Saudi Arabia's King Salman and Ukranian president Petro Poroshenko were among the world leaders past and present accused, as ITV News Correspondent Neil Connery reports:
Icelandic Prime Minister Sigmundur Gunnlaugsson has been accused of hiding millions of dollars of investments in his country's banks behind a secret offshore company. He has denied any wrongdoing.
Footage emerged of him walking out of an interview last month as questions were raised about the company at the centre of the allegations.
David Cameron's father Ian was among the thousands of Mossack Fonseca clients named. Downing Street meanwhile said it was a "private matter" whether the Cameron family still had funds in offshore investments.
In China, the families of at least eight current and former members of the supreme ruling politburo are said to have hidden wealth offshore.
And 23 individuals who had had sanctions imposed on them for supporting the regimes in North Korea, Zimbabwe, Russia, Iran and Syria were said to have been revealed to have been clients of Mossack Fonseca.
How were the records obtained?
German newspaper Suddeutsche Zeitung obtained the files which they shared with the International Consortium of Investigative Journalists.
This includes 107 different media organisations with which they published the story.
Is what the law firm has done illegal?
While there is nothing illegal about using offshore companies, the disclosures are likely to lead to fresh calls for international reform of the way tax havens are able to operate.
HM Revenue and Customs has approached the International Consortium of Investigative Journalists for access to the data and said it would "act on it swiftly and appropriately" if there was any wrongdoing.
What does the law firm say about it?
In a statement, Mossack Fonseca said that for 40 years they have "operated beyond reproach" in Panama and other jurisdictions.
The firm added: "We have never been accused or charged in connection with criminal wrongdoing.
"If we detect suspicious activity or misconduct, we are quick to report it to the authorities.
"Similarly, when authorities approach us with evidence of possible misconduct, we always cooperate fully with them."