Moscow, Dec 24 (UNI) No traces of radiation had been found on 17 out of 20 planes of Russia's leading air carrier Aeroflot, which flew the Moscow-Hamburg route since late November, Russia's chief doctor Gennady Onishchenko today said.

The three remaining planes, which were being examined as part of an investigation into the murder of former KGB spy Alexander Litvinenko in London, last month, will be checked shortly, Onishchenko told RIA Novosti news agency.

The checks on Aeroflot planes started after German police discovered traces of polonium-210, the toxic radioactive isotope used to poison Litvinenko, in several locations in Hamburg visited by Dmitry Kovtun, a Russian businessman and key witness in the murder case.

Police in Germany earlier said traces of radiation might be found on Aeroflot's planes, as Kovtun travelled to Germany on that airline.

Kovtun and another witness, Andrei Lugovoi, met with Litvinenko in a London hotel just before he was hospitalised with symptoms of poisoning, and have themselves undergone radiation checks.

Both were questioned here by a team of British Scotland Yard detectives and officials from Russia's Prosecutor General's Office.

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