Authorities turned away Petro Poroshenko, a member of the Our Ukraine party, who had traveled to St. Petersburg on a private visit February 3. The pro-Western party stood behind the "orange revolution" of 2004 when the Kremlin-backed presidential candidate was defeated.
The reason for Moscow's move "is the current practice, introduced by the Ukrainian side in relation to Russian citizens who have been banned from entering Ukraine," the Russian Foreign Ministry's press service said.
The ministry also cited a blacklist of Russian politicians drawn up by Ukrainian authorities.
"Moscow has repeatedly made it clear that it considers Ukraine's actions to be unfriendly and against the good-neighborly spirit of Russian-Ukrainian relations," the press service said, adding that Moscow had proposed that Kiev abandon its unconstructive policy.
An outspoken television journalist, Mikhail Leontyev, 47, was banned by the Ukrainian National Security Service from entering the ex-Soviet nation in July.
The Ukrainian Security Service said Leontyev, known for making acerbic remarks about Ukraine on a short TV program after the main news on Channel One, was barred for violating regulations of foreigners' stay in Ukraine.
Other victims of the Ukrainian ban included the nationalist leader of Russia's Liberal Democratic Party, Vladimir Zhirinovsky, and MP Konstantin Zatulin.
Relations between Russia and Ukraine became tense after the "orange revolution", which brought Western-leaning President Viktor Yushchenko to power. The two nations also became embroiled in an energy dispute at the beginning of last year after Moscow, which supported Yushchenko's rival Viktor Yanukovych in the 2004 presidential race, raised gas prices for its former ally.
However, diplomatic ties have somewhat thawed since Yanukovych's appointment as prime minister in August last year. The premier has steadily consolidated his authority, with parliament sacking president-appointed ministers and passing a Cabinet law to slash the president's powers.
