Russian prosecutors said Wednesday that they are investigating the possible role of a former top owner in the Yukos oil company in the poisoning death of ex-Russian spy Alexander Litvinenko. The Russian Prosecutor General's office said in a statement that Leonid Nevzlin, who lives in Israel and is a citizen, and other Yukos figures wanted by Russia, could have ordered Litvinenko's murder in London last month as well as the poisoning of another ex-agent, Dmitry Kovtun. It did not give any details of the allegations against Nevzlin. Russia has unsuccessfully pressed for the extradition of a number of Kremlin critics in recent years, including tycoon Boris Berezovsky who lives in Britain. "We are checking the possibility that these crimes could have been ordered and organized by the same group of people who are wanted internationally, one of whom is Leonid Nevzlin," prosecutor's spokeswoman Marina Gridneva said on state television. The statement added prosecutors had formed a special investigative unit and were preparing to file international requests for assistance in the case and possible extradition demands. Channel 1 reported Wednesday night that Nevzlin was currently vacationing in the United States. Litvinenko died in London on Nov. 23 after he was exposed to a rare radioactive element, polonium-210. In a deathbed statement, he accused President Vladimir Putin of ordering his murder, allegations which the Kremlin has dismissed as absurd. Alex Goldfarb, a friend of Litvinenko's active in London's community of Russian expatriates and Kremlin critics, called the latest statement "sheer nonsense," adding it was the Russian government's aim to shift blame from itself. "This is sheer nonsense, a very clumsy effort to shift the blame for this murder," he told The Associated Press. "Everybody knows that all evidence points to Russia. The way the Russian government, the Russian prosecutors are handling it is only adding to that suspicion that it is the Russian government behind this. "I don't think anyone will take this seriously," he said. Nevzlin told the AP last month that Litvinenko had given him a document related to Yukos and said he believed the agent's killing was tied to his investigations into the company. Amir Dan, a spokesman for Nevzlin, dismissed the allegations against the Russian exile. "We all know the ways of the KGB and the Russian government, and these claims are ridiculous and are not worthy of comment," he told the AP. Nevzlin fled Russia after authorities launched a campaign against Yukos, once Russia's top oil producer, in 2003. The company's founder, Mikhail Khodorkovsky, is serving an eight-year sentence for fraud and tax evasion and Yukos' main assets now belong to the state oil group Rosneft. Nevzlin, who according to Forbes magazine had a net worth of about US$2 billion prior to Yukos' collapse, has been charged by Russia with ordering the allegedly business-related, 2002 murder of a married couple. A former Yukos security officer has been jailed since mid-2003 in the case.