Edward Snowden
Edward Snowden mocked Cameron's claim that his father's investment company matters were a private affair Getty Images

Whistle-blower Edward Snowden has joined a growing chorus of people demanding David Cameron's resignation after the prime minister finally admitted to profiting from his father's offshore investments to the tune of £30,000 ($42,208).

The American exiled in Russia expressed his views in a series of tweets mocking the PM alongside Iceland Prime Minister Sigmundur David Gunnlaugsson, who was forced to step down following the so-called Panama Papers leak, and urging Britons to press for Cameron's resignation.

He encouraged British voters to take a stand and join a protest that has been planned outside 10 Downing Street on 9 April to demand the prime minister's resignation. "It's up to the British people, not us. In Iceland, 10% of all voters were in the streets within 24 hours, and for less," he tweeted.

According to the information that has leaked from the Panama law firm Mossack Fonseca, Cameron's late father Ian Cameron's investment company is said to have avoided paying tax in the United Kingdom by having its directors hold board meetings in Switzerland and the Bahamas rather than in London.

Earlier, he claimed no connection with the company but during a recent interview with ITV News, Cameron confessed to profiting from a Panama-based offshore trust set up by his father.

He admitted that he and wife Samantha had shares in the company in 1997, which were sold off in 2010, for which he paid income tax. "I obviously can't point to the source of every bit of money and dad's not around for me to ask the questions now," Cameron said when questioned about the £300,000 ($422,085) he inherited.

The Panama Papers is a collection of 11.5 million confidential documents regarding more than 214,000 offshore companies that have registered offshore companies with the Panama law firm Mossack Fonseca, and were first made public by the German newspaper Süddeutsche Zeitung.