He said a medical examination will show if their organisms contain a dangerous concentration of the radioactive element. Authorities did not identify them by name.
Businessman Dmitry Kovtun met with defector Alexander Litvinenko around the time of his poisoning at the beginning of November. Litvinenko, an outspoken critic of President Vladimir Putin's administration and a close associate of fugitive oligarch Boris Berezovsky, died in a London hospital after four days in a critical condition.
His body was found to contain a lethal dose of radioactive polonium-210. Kovtun is now reported to have been hospitalized with similar symptoms.
Investigators also said traces of polonium-210 have been found on Kovtun's clothes and some articles in the former wife's Hamburg apartment, as well as in other apartments in Hamburg which he visited from October 28 till November 1.
Representatives of the investigative team also said "they have almost no doubt that Dmitry Kovtun brought polonium from Moscow."
British detectives, currently in Moscow for their probe into Litvinenko's murder, earlier spoke with Kovtun through their Russian counterparts.
A team of investigators from the Russian Prosecutor General's Office began questioning Andrei Lugovoi, another key witness in the Litvinenko case, December 8 in the presence of Scotland Yard experts. Lugovoi went to see the former Russian agent in London together with Kovtun.
