Slovakia's Prime Minister Robert Fico is among a handful of global leaders who will attend a scaled-down edition of Russia's Victory Day parade in Moscow this month, Russian state television reported on Sunday.
Following Viktor Orban's defeat in Hungary's elections last month, Fico is now seen as the European Union's most pro-Russian leader.
Both Hungary and Slovakia have continued supplies of Russian gas despite EU efforts to end the bloc's dependence on Russian energy.
Fico also broke with the EU by visiting Moscow in 2024, two years after Russia's full invasion of Ukraine, and met with Russian leader Vladimir Putin in the Kremlin after last year's parade in Red Square, drawing a rebuke from the Slovak opposition and Brussels.
Belarusian President Alexander Lukashenko will also be in Moscow for the celebrations on May 9.
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The parade is one of the main events of the Russian calendar, commemorating the victory of the Soviet Union - of which both Russia and Ukraine were part - over Nazi Germany in World War II, a conflict in which 27 million people were lost.
Moscow will hold a scaled-down version of the parade this year without the usual large display of weapons, the Kremlin said on Wednesday, citing a growing threat of Ukrainian attacks.