5 key cases in the Panama Papers

1 President Vladimir Putin

The Guardian said the Panama Papers showed a network of secret offshore deals and loans worth US$2 billion led to associates of Russian President Vladimir Putin, including concert cellist Sergei Roldugin, a childhood friend of the President. Putin's spokesman Dmitry Peskov says "it's obvious that the main target of such attacks is our President," and claimed that the publication was aimed at influencing Russia's stability and parliamentary elections scheduled for September. Peskov said international media had wrongly focused on Putin instead of other world politicians. In Russia, where the investigation was published by independent Novaya Gazeta, the Panama Papers faced an effective coverage ban. Russian television made no mention of the scandal.

2 Prime Minister David Cameron

The leaks could be embarrassing for British Prime Minister Cameron, who has spoken out against tax evasion and tax avoidance. His late father, Ian Cameron, a wealthy stockbroker, is mentioned in the files, alongside members of his Conservative Party, former Conservative MPs and party donors. Opposition politicians accuse Cameron of failing to implement promises to reform British Crown dependencies - such as the Channel Islands - and overseas territories that act as tax havens. A spokeswoman for HM Revenue and Customs, said the Government would examine the information "and act on it swiftly and appropriately". Ian Cameron created a company in Panama in 1982 that promoted itself as a tax avoidance option.

3 President Petro Poroshenko

In Ukraine, MPs said Parliament should investigate allegations President Petro Poroshenko moved his confectionery business, Roshen, to the British Virgin Islands in August 2014 as fighting between Ukraine and pro-Russian separatists peaked. A senior official from the General Prosecutor's office said there was no evidence the President had committed a crime. Oleh Lyashko, the leader of the Radical Party, urged MPs to initiate impeachment proceedings against the President.

4 Prime Minister Nawaz Sharif

The papers also showed the use of offshore companies by Pakistini Prime Minister Nawaz Sharif's family, including his daughter Mariam and son Hussain who were involved in offshore companies that owned properties in Britain. Pakistani Information Minister Pervez Rasheed denied any wrongdoing on their part.

5 Prime Minister Sigmundur Davíð Gunnlaugssonin

In Iceland thousands of people demonstrated in Reykjavik's Austurvöllur square calling for Prime Minister Gunnlaugssonin's resignation. The Guardian says pressure is mounting for Gunnlaugssonin to step down after the Panama Papers revealed he co-owned a company called Wintris Inc, set up in 2007 in the British Virgin Islands, to hold investments with his wealthy partner, later wife, Anna Sigurlaug Pálsdóttir.

- additional reporting AP