German authorities said today they have found traces of the rare radioactive substance polonium-210 at an apartment visited by a contact of poisoned ex-spy Alexander Litvinenko before they met in London.
Prosecutors said they were investigating Dmitry Kovtun on initial suspicion of improper handling of radioactive material, but said any connection with Litvinenko's death was for British police to clarify.
Investigators said the Russian businessman visited his ex-wife's Hamburg apartment the night before heading to London, where he met Litvinenko on November 1 - the day the former spy is believed to have fallen ill.
Litvinenko was killed by polonium-210. Gerald Kirchner of the German Federal Radiation Protection agency said at a news conference that tests on traces of radiation at the apartment ``clearly show that it is polonium-210''.
Kovtun arrived in Hamburg from Moscow on October 28 on an Aeroflot flight, officials said.
Radiation was found on a couch where Kovtun is believed to have slept in his ex-wife's apartment, on a document he brought to Hamburg immigration authorities and in the passenger seat of the BMW car that picked him up from Hamburg airport, police said.
Kovtun is reportedly being treated in Moscow for symptoms of radiation poisoning. On Saturday, the plane aboard which he flew to London from Hamburg on November 1 tested negative for polonium-210.
Prosecutor Martin Koehnke said Kovtun was not initially treated as a suspect bcause of the possibility that the polonium was inside his body.