BERLIN — The release of a vast trove of documents and other data on offshore financial dealings of wealthy, famous and powerful people around the world raises questions over the widespread use of such tactics to avoid taxes and skirt financial oversight.

Reports by an international coalition of media outlets on an investigation with the Washington-based International Consortium of Investigative Journalists brought to light details of offshore assets and services of politicians, businesses and celebrities, based on a cache of 11.5 million records.

Among the countries with past or present political figures named in the reports are Iceland, Ukraine, Pakistan, Saudi Arabia, Russia and Argentina.

Australia’s tax agency said today it was investigating more than 800 wealthy people for possible tax evasion linked to their alleged dealings with Mossack Fonseca, a Panamanian law firm with international offices that provide offshore financial services.

The Australian Tax Office said in a statement that it had linked more than 120 of those people to an offshore services provider in Hong Kong, but did not name the company.

Ramon Fonseca, a co-founder of Mossack Fonseca — one of the world’s largest creators of shell companies — confirmed to Panama’s Channel 2 television network that documents investigated by the ICIJ were authentic and had been obtained illegally by hackers.

But he said most people named in the reports were not his firm’s direct clients but were accounts set up by intermediaries. He said the firm did not engage in any wrongdoing.

Businessmen, criminals, celebrities and sports stars — the ICIJ said the documents involve 214,488 companies and 14,153 clients of Mossack Fonseca. The nonprofit group said it would release the full list of companies and people linked to them early next month.

The Munich-based German newspaper Sueddeutsche Zeitung said it was offered the data more than a year ago through an encrypted channel by an anonymous source. The source sought unspecified security measures but no compensation, said Bastian Obermayer, a reporter for the paper.

The documents provided to Suddeutsche Zeitung, amounting to about 2.6 terabytes of data, included e-mails, financial spreadsheets, passports and corporate records detailing how powerful figures used banks, law firms and offshore shell companies to hide their assets. The data dated from 1977 through the end of 2015, it said.