A partner at Mossack Fonseca, the Panamanian law firm at the centre of a huge leak of confidential financial data, says it was the victim of a hack.
Ramon Fonseca said the leak was not an "inside job" - the company had been hacked by servers based abroad.
It had filed a complaint with the Panamanian attorney general's office.
Several countries are investigating possible financial wrongdoing by the rich and powerful after the leak of more than 11 million documents.
"We are amazed that nobody has said: 'Hey, a crime has been committed here,'" Mr Fonseca, one of the firm's founding partners, told Reuters news agency.
"The world is already accepting that privacy is not a human right," he told AFP agency separately.
Last week the company reportedly sent an email to its clients saying it had suffered "an unauthorised breach of our email server".
The company has accused media organisations reporting the leak of having "unauthorised access to proprietary documents and information taken from our company" and of presenting this information out of context.
In a letter to the Guardian newspaper on Sunday, the company's head of public relations threatened possible legal action over the use of "unlawfully obtained" information.
The revelations have already sparked political reaction in several countries where high-profile figures have been implicated.
More on the Panama Papers
On Tuesday Iceland's Prime Minister Sigmundur Gunnlaugsson stepped down after the documents showed he owned an offshore company with his wife but had not declared it when he entered parliament.
He is accused of concealing millions of dollars' worth of family assets.
Mr Gunnlaugsson says he sold his shares to his wife, and denies any wrongdoing.
European football body Uefa confirmed on Wednesday that Swiss police had searched its offices in relation to the Panama papers.
It said police had a warrant to look for contracts between Uefa and Cross Trading/Teleamazonas.
The Panama papers suggest current Fifa president Gianni Infantino signed off on a contract with two businessmen who have since been accused of bribery.
Mr Infantino signed off the contract in 2006 as a Uefa director. He says he is "dismayed" that his "integrity is being doubted" and denies any wrongdoing.
Also on Wednesday, Ukraine's President Petro Poroshenko reacted to his name being linked to the papers.
He said he had created an offshore holding company for his confectionery business when he became president in 2014 but not to avoid taxes.
He said: "If we have anything to be investigated, I am happy to do that. This is absolutely transparent from the very beginning. No hidden account, no associated management, no nothing."
Panama Papers - tax havens of the rich and powerful exposed
- Eleven million documents held by the Panama-based law firm Mossack Fonseca have been passed to German newspaper Sueddeutsche Zeitung, which then shared them with the International Consortium of Investigative Journalists. BBC Panorama and UK newspaper The Guardian are among 107 media organisations in 76 countries which have been analysing the documents. The BBC does not know the identity of the source
- They show how the company has helped clients launder money, dodge sanctions and evade tax
- Mossack Fonseca says it has operated beyond reproach for 40 years and never been accused or charged with criminal wrongdoing
- Tricks of the trade: How assets are hidden and taxes evaded
- Panama Papers: Full coverage; follow reaction on Twitter using #PanamaPapers; in the BBC News app, follow the tag "Panama Papers"
- Watch Panorama on the BBC iPlayer (UK viewers only)
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