[JURIST] The UK Foreign Office [official website] said Tuesday that Russia's refusal to extradite the primary suspect [JURIST report] in the murder of British citizen and former Russian intelligence officer Alexander Litvinenko [BBC profile] was "unacceptable." Prime Minister Gordon Brown said his office was still considering how to respond to Russia's announcement Monday that it would not force Russian businessman Andrei Lugovoi to go to trial in the UK, where he has been charged with Litvinenko's murder [JURIST report]. Russian officials say the Russian constitution prohibits the extradition of citizens for criminal trials in other nations. The UK Crown Prosecution Service (CRS) has declined Russian offers to try the suspect in Russia.

Litvinenko and Lugovoi, both former employees of the Federal Security Service of the Russian Federation (FSB) [official website], met in London on November 1, 2006, hours before Litvinenko fell ill to radioactive poisoning from polonium-210 [CDC backgrounder]. Britain and Russia are parties to the European Convention on Extradition 1956 [text] and the CPS and Office of the Prosecutor General of the Russian Federation have also signed a Memorandum of Understanding on Co-operation [text]. AP has more.