WikiLeaks' founder Julian Assange's battle to avoid extradition to the United States received a huge boost on Monday when London's High Court ruled that U.S. assurances over his case were unsatisfactory and he would get a full appeal hearing.

In March, the High Court provisionally gave Assange, 52, permission to appeal on three grounds. But it gave the U.S. the opportunity to provide satisfactory assurances that it would not seek the death penalty and would allow him to seek to rely on a First Amendment right to free speech in a trial.

In a short ruling, two senior judges said the U.S. submissions were not sufficient and said they would allow the appeal to go ahead.