Czech government accuses Russian secret services of being behind an explosion that killed two people at an arms depot in 2014, which President Milos Zeman on Sunday likened to terror attacks.
Romania has said it will expel a Russian diplomat, the latest European country to do so in solidarity with the Czech Republic, which is involved in a spat with Moscow.
The deputy military attache at the Russian embassy in Bucharest, Alexei Grichayev, would be declared "persona non grata... in view of his activities and actions contrary to the Convention of Vienna on diplomatic relations," the foreign ministry said in a statement.
The Czech government has accused the Russian secret services of being behind an explosion that killed two people at an arms depot in the eastern Czech Republic in 2014, which President Milos Zeman on Sunday likened to terror attacks.
After Prague expelled 18 Russian diplomats over the allegations, Moscow retaliated by kicking out 20 Czech embassy staff, sending bilateral relations to their lowest point in decades.
Russian expels Italian diplomat
Russia expelled an Italian diplomat on Monday and called in Italy's ambassador to its foreign ministry over what it said was a groundless move by Rome to expel two Russian diplomats last month.
Italy had expelled two Russian diplomats after police said they had caught an Italian navy captain passing secret documents to a Russian military official in return for money.
Italy said Russia's decision to expel itss deputy naval attaché from Moscow was unjust.
"We consider the decision unfounded and unjust because it is in retaliation to a legitimate measure taken by the Italian authorities in defence of their own security," an Italian foreign ministry statement said.
Italy expelled two Russian diplomats last month after police said they had caught an Italian navy captain passing secret documents to a Russian military official in return for money.
On Tuesday, Czech Interior Minister Jan Hamacek asked his partners in the European Union and NATO to expel Russian diplomats in solidarity, leading neighboring Slovakia as well as the Baltic states of Estonia, Latvia, and Lithuania to announce they would expel a total of seven Russian diplomats.
"Any accusations of Russia in the context of the various events in the Czech Republic is completely unfounded," Kremlin spokesperson Dimitri Peskov told reporters on Monday, adding that the accusations were "without evidence" and caused "extreme harm" to bilateral relations.
Zeman, however, said Sunday that he could see no reason why "there should be 18 spies" at the Russian embassy in Prague.
The alleged agents of Russia's GRU military secret service are the same ones suspected of poisoning former Russian double agent Sergei Skripal and his daughter in Salisbury, England in 2018.
This is a developing story, will be updated.