A giant leak of documents from the internal database of a global law firm based in Panama, Mossack Fonseca, has revealed the offshore holdings of 140 politicians, public officials, and athletes around the world.

The leaks — a collaborative effort by the International Consortium of Investigative Journalists — were obtained by the German newspaper Süddeutsche Zeitung, and contain over 11 million records dating back 40 years. They amount to approximately 3 terabytes of data, including corporate records, financial filings, emails, and more. It is roughly 1,500 times as big as the 1.7 gigabytes of data dumped in 2010 by Wikileaks.

"I think the leak will prove to be probably the biggest blow the offshore world has ever taken because of the extent of the documents," Gerard Ryle, director of the ICIJ, told BBC.

While anonymous company structures hidden in offshore holdings are not illegal, the leaks reveal the extent to which many high-level political figures have relied on shell companies to conceal their wealth, launder money, or evade taxes.

A memorandum from a Mossack Fonseca partner contained in the leak reads, "Ninety-five per cent of our work coincidentally consists in selling vehicles to avoid taxes," according to The Guardian.

To that end, offshore companies can be also be used for more nefarious purposes, such as to do business with blacklisted firms or individuals.