The Panama Papers is a huge cross-border journalism collaboration by the International Consortium of Investigative Journalists (ICIJ) that has been analyzing millions of records leaked from an international law firm based in Panama.
In them, UBS and HSBC Switzerland are named alongside 500 banks worldwide as having created offshore companies for their customers through Mossack Fonseca, a legal law firm which administers offshore firms in tax havens including Switzerland, the British Virgin Islands and Cyprus.
According to the ICIJ, Mossack Fonseca worked with 1,223 banks, law firms and other intermediaries in Switzerland, the third most after Hong Kong and the UK.
The largest offshore leak in history, The Panama Papers contain details on more than 214,000 offshore entities connected to people in more than 200 countries including celebrities and politicians.
Among those named are some 140 politicians and public officials around the world including the president of Ukraine, Pakistan and Iceland's prime ministers and the king of Saudi Arabia, plus associates of Russian president Vladimir Putin.
Also named in the papers as having used offshore companies created by Mossack Fonseca are several figures connected to the scandal surrounding world football's governing body, Zurich-based Fifa, said the ICIJ.
They include Michel Platini, president of Uefa, also based in Switzerland, who was handed a six-year ban for receiving an irregular payment from former Fifa president Sepp Blatter, who was also banned.
Jérôme Valcke, former secretary general of Fifa and Blatter's right hand man, who was banned on corruption charges in September, also appears in the documents as owner of a British Virgin Islands company.
Furthermore, the documents reveal that the law firm of a member of Fifa's ethics committee had business relationships with high-level Fifa executives who have since been banned by the committee.
According to the ICIJ, Juan Pedro Damiani and his law firm did work for at least seven offshore companies linked to former Fifa vice president Eugene Figueredo who has been charged with fraud by US authorities.
The records also show that Damiani's firm served as an intermediary for a company linked to father and son Hugo and Mariano Jinkis, businessmen who have been charged with fraud and money-laundering, said the ICIJ.
The ICIJ points out that the leaked documents do not implicate Damiani and his firm in illegal conduct.
However the link raises further questions in the ongoing Fifa scandal which erupted last May with a raid on the world football governing body's headquarters in Zurich.
Using offshore structures is entirely legal, however the anonymity of such structures can allow corruption to fall under the radar.
Speaking to The Guardian, a spokesperson for Mossack Fonesca said it complies with anti-money-laundering laws and carries out thorough due diligence on all its clients.
Contacted by Swiss paper Le Temps, John Christensen, director of Tax Justice Network, said: “During its nearly 40 years history, Mossack Fonseca has been associated with a multitude of criminals for which it creates secret and sophisticated structures allowing them to pursue their activities.”