Mykola Zhulinskyy, a senior aide to Ukrainian President Viktor Yushchenko, was denied entry to Russia late June 5 while traveling to St. Petersburg.
The incident took place just hours after Aleksandr Dugin, the leader of Russia's nationalist Eurasia movement, was deported from Ukraine.
Kyiv has blocked a number of Russian officials and politicians in past years, and Russia has responded by expelling Ukrainian citizens.
(AP)