Ukraine is marking this week 1,020 years since Christianity was adopted in Kievan Rus, with church services, processions, and other events to mark the anniversary.
The ministry said the Ukrainian ambassador to Russia was summoned to the ministry on Friday, where he discussed the issue with First Deputy Foreign Minister Andrei Denisov.
The Ukrainian Orthodox Church, subordinate to the Moscow Patriarchy, is currently the only Ukrainian church with a canonical standing in Eastern Orthodoxy and has full communion with the other Eastern churches. According to official data, it is the largest religious body in the country, predominant in the east and south.
Kiev Patriarchy officials have recently stepped up contacts with the Church of Constantinople, also known as the Ecumenical Patriarchate, seeking "to return Ukraine to the Mother Church." The drive has been actively backed by President Yushchenko and the country's other top officials against the backdrop of ongoing tensions in relations with Russia.
The Christianization of Kiev dates from late 988, when Prince Vladimir the Great was baptized at Chersonesos, in the Crimea. He then baptized his family and people in Kiev and destroyed wooden statues of Slavic pagan gods.
Russian church officials said on Thursday that the Moscow and Constantinople Patriarchates had agreed ahead of the holiday "to rule out" the participation of leaders of the "schismatic churches" in services and other events in Kiev to celebrate the anniversary.
