An extensive investigation into the offshore financial dealings of the rich and famous was published by an international coalition of media outlets Sunday, based on a vast trove of documents said to have been leaked by an anonymous source.
The International Consortium of Investigative Journalism, a nonprofit organization based in Washington, said the cache of 11.5 million records detailed the offshore holdings of a dozen current and former world leaders, as well as businessmen, criminals, celebrities and sports stars.
A co-founder of the Panamanian-based law firm where the documents originated confirmed the authenticity of the papers being used in articles published by more than 100 news organizations around the world. Ramon Fonseca told Panama's Channel 2 television network that the documents were acquired illegally in a hacking attack.
The German newspaper Sueddeutsche Zeitung said it first received the data more than a year ago. The Munich-based daily was offered the data through an encrypted channel by an anonymous source who requested no monetary compensation and asked only for unspecified security measures, said Bastian Obermayer, a reporter for the paper.
The data concerned internal documents from the Panama-based law firm Mossack Fonseca.
Fonseca said most of the people being named in news reports about big offshore accounts were not the firm's direct clients, saying the accounts were mainly established by financial intermediaries. He also said the firm did not engage in any wrongdoing. "We are not responsible for the actions of a corporation that we set up," he said in the TV interview.
Panamanian President Juan Carlos Varela issued a statement saying his government would cooperate "vigorously" with any judicial investigation arising from the leak of the law firm's documents.
ICIJ said the law firm's leaked internal files contain information on 214,488 offshore entities connected to people in more than 200 countries and territories. It said it would release the full list of companies and people linked to them early next month.
Among the countries with past or present political figures named in the reports are Iceland, Ukraine, Pakistan, Saudi Arabia, Russia and Argentina.
Iceland's prime minister, Sigmundur David Gunnlaugsson, was asked by Sweden's SVT television about a company called Wintris. He responded by insisting that its affairs are above board and calling the question "completely inappropriate," before breaking off the interview.
In Russia, the Kremlin last week said it was anticipating what it called an upcoming "information attack."
Russian President Vladimir Putin's spokesman, Dmitry Peskov, told reporters that the Kremlin had received "a series of questions in a rude manner" from an organization that he said was trying to smear Putin, whose name did not appear in the documents.
"Journalists and members of other organizations have been actively trying to discredit Putin and this country's leadership," Peskov said.
The ICIJ said the documents included emails, financial spreadsheets, passports and corporate records detailing how powerful figures used banks, law firms and offshore shell companies to hide their assets. The data spanned a time frame of nearly 40 years, from 1977 through the end of 2015, it said.
"It allows a never-before-seen view inside the offshore world — providing a day-to-day, decade-by-decade look at how dark money flows through the global financial system, breeding crime and stripping national treasuries of tax revenues," the ICIJ said.
Meanwhile, the British government asked on Monday for a copy of leaked data so it could act on any possible tax evasion.
The leak could be embarrassing for Prime Minister David Cameron. His late father, Ian Cameron, is mentioned alongside some members of his Conservative Party in the upper house of parliament, former Conservative lawmakers and party donors, British media reported.
When contacted by Reuters, Cameron's office declined to comment.
Reuters and the Associated Press contributed. This article originally appeared on NBCNews.com.