London, June 11 (RHC)-- WikiLeaks founder Julian Assange's appeal against extradition from Britain to the United States will be heard next month, court officials in London said on Tuesday.

The 52-year-old Australian-born political prisoner is fighting extradition to the U.S. where he is charged on 18 courts, nearly all under the Espionage Act, relating to WikiLeaks' mass release of secret U.S. documents -- the largest security breaches of their kind in U.S. military history.

WikiLeaks revelations showed the extensive war crimes committed by the United States, publishing U.S. military logs from the wars of aggression against Afghanistan and Iraq, and U.S. diplomatic cables.

Last month, the High Court in London granted him permission for an appeal over his argument that he might not be able to rely on his right to free speech at a trial in a U.S. court.

That appeal will now be held on Tuesday, July 9th and Wednesday, July 10th, according to a statement from the spokesperson for Britain's Judicial Office in London.