The Panama Papers lift the lid on how offshore companies are used by the global elite to conceal the ownership and control of assets and property worth billions.

Members of the The International Consortium of Investigative Journalists, including The Irish Times, have spent more than a year examining a cache of 11.5 million documents and records from Panama-based Mossack Fonseca, one the biggest providers of offshore services to individuals, companies and middle men who advise them.

The leaked data covers nearly 40 years, from 1977 through the end of 2015 . The files list nearly 15,600 paper companies that banks set up for clients who want keep their finances under wraps, including thousands created by international giants UBS and HSBC.

The law firm’s leaked internal files contain information on 214,488 offshore entities connected to people in more than 200 countries and territories.

Secret companies around the world

The data includes emails, financial spreadsheets, passports and corporate records revealing the secret owners of bank accounts and companies in 21 offshore jurisdictions, from Nevada to Singapore to the British Virgin Islands.

ICIJ will release the full list of companies and people linked to them in early May.

The International Consortium of Investigative Journalists is a global network of investigative journalists who collaborate on in-depth investigative stories. There are 376 journalists from 109 media outlets in 76 countries involved the the Panama Papers project.

The ICIJ was founded in 1997 as a project of the Center for Public Integrity, a nonpartisan, nonprofit investigative news organisation founded by veteran US journalist Charles Lewis. Its remit is to focus on issues that do not stop at national frontiers: cross-border crime, corruption, and the accountability of power.

It is based in Washington DC and works with leading international news organisations including The Irish Times, the Guardian, the BBC, Le Monde, the New York Times, the Sydney Morning Herald and the Washington Post.

The ICIJ relies on charitable foundations and financial support from the public. Recent ICIJ funders include: Adessium Foundation, Open Society Foundations, The Sigrid Rausing Trust, The Ford Foundation, The David and Lucile Packard Foundation, Pew Charitable Trusts and Waterloo Foundation.