A year-long investigation by global journalists has revealed how a shady network of rich and powerful world leaders use offshore tax havens to hide their vast wealth, launder money, dodge sanctions and evade taxes despite legal requirements in place that should prevent exactly those things from occurring.

Dubbed the Panama Papers, a cache of 11 million internal documents — 2.6 terabytes worth — from Panamanian law firm Mossack Fonseca shine a light on secret offshore holdings from 128 politicians and public officials across the globe, including 12 current and former world leaders.

Dealing in offshore business is not illegal. Eastern Europe's elite have for years used them to keep their assets out of reach of company raiders, for example. But the use of offshore tax havens in the manner and to the extent the Panama Papers shows by heads of state and top officials raises serious questions.

The files expose how associates of Russian President Vladimir Putin secretly shuffled as much as $2 billion through banks and shadow companies at his behest. They highlight how Ukrainian President Petro Poroshenko increased his wealth after being elected in 2014 and while his soldiers were dying in eastern Ukraine. They also show secret offshore companies linked to the families and associates of Egypt's former president Hosni Mubarak, Libya's former leader Muammar Gaddafi and Syria's president Bashar al-Assad.They reveal others controlled by the prime ministers of Iceland and Pakistan, the king of Saudi Arabia and the children of the Azerbaijan's president.

In all, they include at least 33 people and companies blacklisted by the U.S. government due to evidence that they've done business with Mexican drug cartels, extremist organizations like Hezbollah or rogue nations like North Korea and Iran.

The investigation marks one of the biggest leaks in journalistic history. It is larger than the U.S. diplomatic cables released by WikiLeaks in 2010, and the secret intelligence documents leaked by NSA whistleblower Edward Snowden in 2013.

Snowden on Twitter called the Panama Papers disclosure "the biggest leak in the history of journalism." Within minutes of the documents' release at 2 p.m. EST, #PanamaPapers was trending on the social network.

Biggest leak in the history of data journalism just went live, and it's about corruption. https://t.co/dYNjD6eIeZ pic.twitter.com/638aIu8oSU — Edward Snowden (@Snowden) April 3, 2016

The Mossack Fonseca documents were first leaked to German newspaper Süddeutsche Zeitung more than a year ago. Investigative journalists in countries around the word have been sifting through them ever since.

"The source wanted neither financial compensation nor anything else in return, apart from a few security measures," Süddeutsche Zeitung said of its confidential source. The newspaper shared the documents with the International Consortium of Investigative Journalists (ICIJ) and the Organized Crime and Corruption Reporting Project (OCCRP). The organization then launched a global reporting effort involving 107 media organizations in 78 countries.

View of a sign outside the building where Panama-based Mossack Fonseca law firm offices are located in Panama City, April 3, 2016. Image: RODRIGO ARANGUA/AFP/Getty Images

This video report explains how the investigation was carried out.

Eastern European leaders, specifically, Putin and Poroshenko, feature prominently in the documents. But the leaks also tie several other leaders, including Iceland's prime minister, to secret offshore companies and dubious deals.

The Panama Papers' biggest revelations and fallout

ICIJ explains the revelations this way:

The documents show that banks, law firms and other offshore players have often failed to follow legal requirements that they make sure their clients are not involved in criminal enterprises, tax dodging or political corruption. In some instances, the files show, offshore middlemen have protected themselves and their clients by concealing suspect transactions or manipulating official records.

Some revelations of particular interest include:

Putin's close friend and godfather to his child, concert cellist Sergei Roldugin, agreed to be a front for the Russian president to launder $2 billion to offshore accounts. They also reveal that Putin's friends and associates have made millions from their association with the president. The operation was run by Bank Rossiya, which is under American and European sanctions following Moscow's annexation of Crimea.

Poroshenko became the sole shareholder in an offshore British Virgin Islands company while his army was surrounded and hundreds of troops were slaughtered by Russian forces in the eastern town of Ilovaisk in August 2014.

Iceland's prime minister, found to be using offshore tax havens, this week could face calls in parliament for a snap election after the leaks came to light.

The files contain details of offshore dealings conducted by British Prime Minister David Cameron's late father. Cameron has led the push in Britain for tax-haven reform.



World-famous soccer player Lionel Messi and his father were found to be owners of Panama company Mega Star Enterprises Inc., adding to a list of shell companies known to be linked to the star. His offshore dealings are currently the target of a tax evasion case in Spain.



Of course, there are many more, all of which can be found here.

The Kremlin and other administrations were not available for comment on Sunday. Poroshenko's office told Mashable a statement would not be released until Monday.

.@poroshenko's office tells me no statement tonight. Unlikely we'll hear from the Ukrainian president on #panamapapers until Monday. — Christopher Miller (@ChristopherJM) April 3, 2016

Confronted about the connection to an offshore tax haven ahead of the documents' release, Gunnlaugsson walked out on journalists during an interview.

Mossack Fonseca in a statement insisted it has complied with all laws and regulations.

"For 40 years Mossack Fonseca has operated beyond reproach in our home country and in other jurisdictions where we have operations," the law firm said in a statement. "Our firm has never been accused or charged in connection with criminal wrongdoing."

Due to the hyped rollout on social media by OCCRP and ICIJ in the days leading up to the documents' release, and the revelations themselves, the Internet responded to the news as it often does — with memes.

When the office space is just an address... #PanamaLeaks pic.twitter.com/jxPbkNFk8A — Glenn Kates (@gkates) April 3, 2016

Check the cello case for Putin's billions #Roldugin pic.twitter.com/MUFubH5gqf — Leonid Ragozin (@leonidragozin) April 3, 2016

Good night. My bed helps ease back pain.#panamapapers pic.twitter.com/sL7d6kvHV2 — Vladimir Putin (@DarthPutinKGB) April 3, 2016

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