Coroner Robert Owen Thursday told a Royal Courts of Justice hearing in London he was forced to postpone the inquiry because both the British and Russian authorities have been slow to hand over needed materials, RIA Novosti reported.
Litvinenko, a former Federal Security Service officer from Russia, was poisoned in London in 2006, shortly after he received British citizenship. He was an opponent of the Kremlin and accused Russia's security services of blowing up residential buildings in Moscow and other cities in an effort to ensure Vladimir Putin's victory in the 2000 presidential election.
British authorities have said Andrei Lugovoi, also an ex-FSB officer and current lawmaker in Moscow, is a main suspect in the case. Lugovoi has denied the allegations and the Kremlin has refused to extradite him.
2014: The Year in Music [PHOTOS]