Czech President Milos Zeman has said there are two theories about what caused the 2014 arms depot blast that has sparked a severe diplomatic rift with Russia, and that both must be investigated.
Speaking for the first time about the incident during a televised address to the nation on April 25, Zeman said that one version of events is that Russian intelligence was involved in the deadly explosion.
The other version, he said, was that the blast was caused by inexpert handling of ammunition.
"I take both lines [of investigation] seriously and I wish that they are thoroughly investigated," Zeman said.
Prime Minister Andrej Babis on April 17 announced that investigators from the Czech intelligence and security services had provided "unequivocal evidence" that there was "reasonable suspicion regarding a role of members of Russian military intelligence GRU's unit 29155 in the explosion of the munition depot in Vrbetice in 2014."
Citing the report by the Czech Security Information Service, Zeman said that there was "neither proof nor evidence" that the two Russian GRU agents being sought regarding possible involvement in the explosion were at the arms depot.
"I hope that we will determine the truth and find out whether this suspicion [of Russian intelligence involvement] is justified," Zeman said. "If that is the case -- although I support fair relations with all important countries -- the Russian Federation would have to pay the price of this presumed terrorist act."
Zeman suggested that eliminating the Russian company Rosatom from consideration in a bid to construct a new nuclear plant would be one possible punishment. However, he also said that if Russia were cleared of responsibility it "could bear serious consequences for our internal politics."
Zeman, whose powers as president are largely ceremonial, has often expressed pro-Russian views and is seen as being friendly toward Moscow.
The blast in Vrbetice on October 16, 2014, set off 50 metric tons of stored ammunition. Two months later, another blast of 13 tons of ammunition occurred at the same site.
In response, the Czech government announced the expulsion of 18 Russian diplomats it considered to be spies, setting off a string of tit-for-tat moves between Prague and Moscow.
In what is considered to be the worst spat between the former Cold War allies since communist rule ended in Czechoslovakia in 1989, the two sides exchanged ultimatums and hiked the number of diplomatic expulsions.
On April 19, Russia announced that 20 employees at the Czech Embassy in Moscow would be expelled.
On April 23, Czech Foreign Minister Jakub Kulhanek said that the number of people allowed by the Czech Republic and Russia at their respective embassies would be limited to 32, including seven diplomats.
The Czech Foreign Ministry has given Russia until the end of May to cut the number of its personnel at its embassy in Prague by 63 people.
Russia, which has denied any involvement in the arms depot blast, has pledged to respond.
Czech media has reported that the ammunition and weaponry destroyed in the first Vrbetice blast, which killed two people, was intended for Ukrainian forces fighting against Russia-backed separatist troops in eastern Ukraine.
The two Russian intelligence officers sought in relation to the explosion are the same GRU officers accused of a nerve-agent poisoning in England in 2018 that targeted former Russian double agent Sergei Skripal.
Skripal and his daughter survived the attack carried out with what British investigators determined was the Soviet-engineered nerve agent Novichok.
A British woman who accidentally came into contact with the substance died.