A former Swiss banker has handed over to the WikiLeaks website details of 2000 individuals and institutions who he says use banking secrecy to evade taxes.
At a news conference in London, Rudolf Elmer said the two computer discs contained the names of multimillionaires, corporations and hedge funds, as well as 40 politicians, from several countries.
The founder of the whistleblowing website, Julian Assange, has confirmed WikiLeaks will publish the details once the information has been vetted, the BBC reports.
Mr Elmer is scheduled to go on trial in Switzerland on Wednesday for breaking bank secrecy laws.
The banker, who has previously given data to WikiLeaks, was fired from Swiss bank Julius Baer in 2002.
The WikiLeaks head noted that previous data from the bank, provided by Mr Elmer, had shed light on tax evasion, the hiding of proceeds of criminal acts and the protection of assets of those about to fall out of political favour.