The financial squeeze has been put onto Wikileaks, with MasterCard refusing to process donations to the whistleblower site and the suspension of the personal bank account of founder Julian Assange in Switzerland.
The withdrawal of payment facilities by MasterCard follows a similar decision by PayPal. Would-be supporters are only currently able to donate funds via Visa to a website hosted in Iceland.
Also, the Swiss post office's bank PostFinance has frozen a bank account run by Assange. The account held 31,000 euros of funds made up of a mixture of Assange's personal assets and donations to a legal defence fund, the BBC reports.
PostFinance said the account was suspended because Assange provided false residency details when he opened the account.
The move put the Swiss bank in the firing line of hacktivists from the loosely-banded Anonymous collective, who have launched a denial of service attack against postfinance.ch as part of a wider pro-Wikileaks and anti-censorship campaign that launched with an attack on a PayPal blog over the weekend.
Both attacks were prompted by the respective organisations' decisions to freeze accounts used by Wikileaks or Assange.
Wikileaks' decision to start publishing leaked US diplomatic cables late last month has created far more heat than its previous decisions to publish logs from the conflicts in Afghanistan and Iraq. It's tempting to speculate that US authorities are applying pressure on various banks and financial service firms in order to choke off sources of funding to the site.
Julian Assange was arrested by UK police on Tuesday, and is due to be questioned over allegations of rape made by Swedish authorities that he strongly denies. Assange, the subject of a European arrest warrant, surrendered himself into custody after making an appointment to turn himself into cops at a London police station. ®
1) Be careful of fake Wikileaks sites and supposed torrents of diplomatic cables - cybercrooks have inevitably begun using interest in the affair to distribute malware to the unwary, security watchers warn.
2) While the finances of Wikileaks are politically important, the far more significant economic problem of the stability of banks has begun to exercise inspirational footballer and sometime philosopher Eric Cantona.
Red Eric has called on his fellow French citizens to withdraw funds from their bank accounts on Tuesday in protest at the banking system. Government ministers and banks had unsurprisingly condemned the move. Finance minister Christine Lagarde has dismissed the protest as "grotesque" and "not serious", The Guardian reports.