Panama Papers' Source Explains Motivation Behind Leak

— -- The source who leaked confidential information included in the so-called Panama Papers has come forward to explain why the documents were released and that more information could come.

The source used the name John Doe last year when contacting German newspaper Süddeutsche Zeitung. John Doe's 1,800-word statement was released today by the International Consortium of Investigative Journalists, a worldwide network of reporters who team up on in-depth investigative stories.

"Income inequality is one of the defining issues of our time," the statement begins, asking why its "sudden acceleration" has many people "helpless to stop its steady growth."

"The Panama Papers provide a compelling answer to these questions: massive, pervasive corruption," John Doe writes.

The 11.5 million leaked files exposed the alleged dealings of a law firm in Panama called Mossack Fonseca, according to the journalists’ group, which published the Panama Papers last month.

The files reportedly show that Mossack Fonseca, which facilitates the incorporation of offshore entities, worked with more than 14,000 banks, law firms and companies from 1977 through 2015 to create tax havens for the rich and powerful. The law firm has denied that it has acted illegally.

The source denies working for any government or intelligence agency, directly or as a contractor and "never have."

"My viewpoint is entirely my own, as was my decision to share the documents with Süddeutsche Zeitung and the [investigative journalists’ group], not for any specific political purpose, but simply because I understood enough about their contents to realize the scale of the injustices they described," John Doe writes.

"ICIJ and its partner publications have rightly stated that they will not provide them to law enforcement agencies," the source said in the statement. "I, however, would be willing to cooperate with law enforcement to the extent that I am able."

President Obama announced today steps to combat money laundering and tax evasion. The U.S. Treasury Department finalized its “customer due diligence” rule, which requires financial institutions to find out and verify who actually owns the companies that use banking services.

"In recent months, we've seen just how big a problem corruption and tax evasion have become around the globe," Obama said today. "We saw what happened with the release of the Panama Papers and we've seen the degree to which both legal practices of tax avoidance that are still unfair and bad for the economy as well as illegal practices that in some cases involve nefarious activities continue to exist and spread."

Offshore bank accounts are not inherently illegal, and they can have many legitimate uses. But they have also been known to be used by both legitimate and criminal enterprises to hide money and avoid paying taxes.

The leaked documents "show that banks, law firms and other offshore players have often failed to follow legal requirements that they make sure their clients are not involved in criminal enterprises, tax dodging or political corruption," according to the investigative journalists’ group.

As a result of the leak, authorities around the world have launched investigations into possible illegal activity among various companies and public figures. Iceland's Prime Minister Sigmundur Davíð Gunnlaugsson resigned last month amid accusations that he and his wife created a shell company in the British Virgin Islands that created a conflict of interest.

Mossack Fonseca did not respond to ABC News’ requests for comment.

But the Panamanian law firm Thursday said it sent a cease-and-desist letter to the International Consortium of Investigative Journalists regarding the group’s announcement that it will make public additional information Monday.

"The letter urges the ICIJ to abstain from this action taking into consideration that it is based on the theft of confidential information and is a violation of the confidentiality agreement between attorney and client, which we must protect," Mossack Fonseca said in a statement Thursday.

"It is important for us to make clear that we operate, in all jurisdictions, under strict compliance with the law and regulations of the industry in all services provided, respecting strong client identification norms."