Czech police said on Saturday they were searching for two men carrying various passports, including Russian passports in the names of Alexander Petrov and Ruslan Boshirov.
The names matched those used by the two suspects in the attempted poisoning of former Russian spy Sergei Skripal and his daughter Yulia with the Soviet-era nerve agent Novichok in the English city of Salisbury in 2018. Russia has denied involvement in the attack.
Czech Prime Minister Andrej Babis had earlier said Prague was expelling 18 Russian diplomats over suspicions that Russian intelligence services had been involved in an ammunition depot explosion in 2014.
(Reporting by Jan Lopatka; Editing by Kevin Liffey)
