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.

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.