The complaint follows threats of legal action against the card schemes, who have refused to process payments for WikiLeaks following its release of a slew of damaging diplomatic US cables late last year.

WikiLeaks says the financial blockade has so far cost it $15 million in lost donations.

The complaint, filed by WikiLeaks and its Icelandic processing partner DataCell, alleges that Visa and MasterCard have breached antitrust provisions set out by Articles 101 and 102 of the EU Treaty.

It claims the block on payments constitutes an abuse of their dominant position in the European cards market, where they account for about 95% of plastic transactions.