Prague - The Czech Republic has expelled two Russian diplomats after a Russian embassy employee spread a hoax about a planned poison attack on three Prague politicians, officials said on Friday.

In April, Respekt newspaper cited security sources as saying that a Russian national using a diplomatic passport had arrived in Prague carrying ricin, a toxic poison that can be used as a biological weapon.

Around the same time, three Prague politicians who had each made political gestures that angered Russia were placed under police protection.

“One embassy employee sent deliberately made-up information about a planned attack on Czech politicians to BIS,” said Prime Minister Andrej Babis, referring to the Czech intelligence service.

“We have adopted appropriate and adequate measures and declared two embassy staff personae non gratae.”

The case soured already shaky relations between Prague and the Kremlin, with Russian foreign ministry spokeswoman Maria Zakharova saying in April that the Respekt report was “misinformation” and “sick fantasies”.

One of the three politicians named in the hoax, Ondrej Kolar, had spearheaded the April removal of a Cold War-era statue dedicated to Soviet general Ivan Konev -- a hero to many Russians but a symbol of Soviet-era oppression to many Czechs.

Another of those targeted, Prague mayor Zdenek Hrib, supported renaming the Prague square where the Russian embassy is based after Boris Nemtsov, a Russian opposition leader murdered in 2015.

And the district run by Pavel Novotny, the third politician mentioned in the hoax, installed a memorial to the so-called Vlasov Army -- Red Army defectors who helped to liberate Prague in May 1945.