Russia may be behind an attempted arson attack on Prague city buses last week, Czech Prime Minister Petr Fiala said on Monday.
Police said they arrested a 26-year-old man on Saturday in connection with the foiled plot and charged him with terrorism.
"There is suspicion that the attack was organised and financed probably from Russia," Fiala told a news conference.
"It is part of a hybrid war waged against us by Russia against which we have to defend ourselves and which we must stop. Russia is repeatedly trying to sow unrest, undermine citizens' trust in our state."
Russia has not responded
The Russian embassy in Prague had no immediate comment.
The Czech Republic is a NATO member and a strong supporter of Ukraine in its defence against Russia.
Police said before the arrest the suspect was Spanish-speaking man from South America.
They said he had been in the Czech Republic for five days before the attempted attack on Wednesday night. He failed to carry out the attack due to the alertness of staff at the Prague bus depot, police said.
Poland, another NATO member, has accused Russia of attempting to destabilise the country, including through sabotage and arson, because of its role in supplying military aid to its neighbour Ukraine. Moscow has dismissed allegations.
Last month, Poland's Internal Security Agency said it had detained a Pole and two Belarusian citizens suspected of setting fire to facilities in various parts of the country. Others have also been arrested for acts of sabotage that Polish officials said were committed on the orders of Russian services.
The Czech Republic blamed Russia for causing a series of unexplained explosions at an ammunition depot in 2014, and expelled dozens of Russian diplomats after it said evidence came to light in 2021.