ITV News reporter Mark McQuillan looks at the two attacks and the men suspected of being behind both
Two Russian men suspected of carrying out the Salisbury poisonings are being linked to a 2014 explosion at an arms depot in the Czech Republic.
Czech police’s organised crime unit is hunting two foreign citizens identified as Alexander Petrov, 41, and Ruslan Boshirov, 43. Authorities said both were using Russian passports while in the Czech Republic.
Police said Petrov and Boshirow visited the country, including the Zlin region where the explosion took place, between October 11 and October 16 in 2014.
The Czech Republic said it was expelling 18 Russian diplomats who it had identified as spies in the case.
In response, Russia ordered 20 Czech diplomats to leave the country by the end of Monday.
The two men linked to the explosion and Salisbury poisoning were also using passports issued by Moldova under a name of Nicolai Popa and another issued by Tajikistan for Ruslan Tabarov.
They said the two also visited the capital of Prague and another northeastern Czech region.
The 2014 explosion shook a depot in Vrbetice, 205 miles southeast of Prague, killing two employees of a private company that was renting the site from a state military organisation.
Another explosion of 13 tons of ammunition occurred in the depot on December 3 of that same year.
Czech Prime Minister Andrej Babis said the move to expel the Russian diplomats is based on “unequivocal evidence” provided by the Czech intelligence and security services that points to the involvement of Russian military agents in the massive explosion in an eastern town that killed “two innocent fathers.”
Foreign Secretary Dominic Raab said: "The UK stands in full support of our Czech allies, who have exposed the lengths that the Russian intelligence services will go to in their attempts to conduct dangerous and malign operations in Europe.
"This shows a pattern of behaviour by Moscow, following the Novichok attack in Salisbury. My sympathies are with the families of the victims in Vrbetice.
"We are as determined and committed as ever to bring those responsible for the attack in Salisbury to justice, and commend the actions of the Czech authorities to do the same. Russia must desist from these actions, which violate the most basic international norms."
Petrov and Boshirov were identified as officers from the Russian military intelligence service, also known as the GRU, by the former prime minister Theresa May shortly after the Salisbury poisonings.They were charged in absentia in 2018 for conspiracy to murder former Russian spy Sergei Skripal and his daughter, Yulia, with the Soviet nerve agent Novichok.
Dawn Sturgess died three months after the Skripals' poisoning after she and her partner Charlie Rowley fell ill after coming into contact with Novichok. Mr Rowley survived.
Detective Sergeant Nick Bailey, the first officer to enter the Skripals' home, also fell seriously ill and announced he was quitting the force in October after serving for 18 years.
Watch ITV News Correspondent Neil Connery's report about the Salisbury poisonings in 2018:
The Czech announcement came two days after the US said it was expelling 10 Russian diplomats and imposing sanctions against several dozen people and companies, holding the Kremlin accountable for interference in last year’s presidential election and the hacking of federal agencies.
Babis said President Milos Zeman, who is known for his pro-Russian views, has been informed about the development and has “expressed absolute support for us.”
He said the investigation into the case has not yet been completed but thanked the country’s security forces for their “professional job.”
Russian Foreign Ministry spokeswoman Maria Zakharova said her country would answer the Czech move.
“Prague is well aware of what will follow such tricks,” Zakharova was quoted by the RIA Novosti news agency.