Authorities across the globe have opened investigations into the activities of the world's rich and powerful after a cache of leaked documents from a Panamanian law firm showed possible wrongdoing using offshore company structures.

The "Panama Papers" have cast light on the financial arrangements of high profile politicians and public figures and the companies and financial institutions they use for such activities. Among those named in the documents are friends of Russian President Vladimir Putin and relatives of the leaders of China, Britain, Iceland and Pakistan, and the president of Ukraine.

Leading figures and financial institutions responded to the massive leak of more than 11.5 million documents with denials of any wrongdoing as prosecutors and regulators began a review of the reports from the investigation by the U.S.-based International Consortium of Investigative Journalists (ICIJ) and other media organizations.

Following the reports, China has moved to limit local access to coverage of the matter with state media denouncing Western reporting on the leak as biased against non-Western leaders.

France, Australia, New Zealand, Austria, Sweden and the Netherlands are among nations that have commenced investigations, and some other countries, including the United States, said they were looking into the matter.

Mossack Fonseca, the Panamanian law firm at the center of the leaks, has set up more than 240,000 offshore companies for clients around the globe and denies any wrongdoing. It calls itself the victim of a campaign against privacy and claims media reports misrepresent the nature of its business.

In a printed statement given to Reuters by a staff member at Mossack Fonseca's Hong Kong office on Tuesday, the firm said it has never been charged with or formally investigated for criminal wrongdoing in its nearly 40 years of operation.

"We do not advise clients on how to operate their businesses. We don't link ourselves in any way to companies we help incorporate," the firm said in the statement.

"Excluding the professional fees we earn, we don't take possession of clients' money, or otherwise have anything to do with any of the direct financial aspects related to operating these businesses."

Mossack Fonseca also said it supports international initiatives requiring greater transparency of newly incorporated companies and trusts and has implemented such measures as part of its own due diligence.