Moscow- Russian investigators said Germany had handed them documents related to the 2006 murder by polonium poisoning of Russian spy defector Alexander Litvinenko in central London, news agency RIA- Novosti reported on Thursday.

German police were involved in the investigation when Russian businessman Dmitry Kovtun, now living in Germany, was found to have met with Litvinenko on the day his poisoning with radioactive polonium-210.

The documents were delivered "in response to a request from Russia to provide the Russian investigation with certain materials on the criminal case," Vladimir Markin, a spokesman for the Investigation Committee of the Russian Prosecutor General's Office, said Thursday.

Material compiled by German investigators related to an attempt on Kovtun's life, Markin said.

British detectives suspect Kovtun's business partner, another ex- secret service agent Andrey Lugovoi, but Moscow has refused London's requests for his extradition and in December Lugovoi was elected a member of parliament, granting him immunity. (dpa)