Relations between Russia and the Vatican have been further strained, after Russia refused entry to a Polish Roman Catholic bishop. The move comes soon after an Italian priest was denied re-entry into Russia.
The Vatican accused Russia of violating religious freedoms, after border guards refused to allow a Polish bishop to return to his diocese in Siberia.
Bishop Jerzy Mazur was denied entry on Friday, when guards at Moscow's international airport took away his multi-entry visa and sent him back to Warsaw. He was on his way to his diocese in the Lake Baikal region of Siberia.
The Vatican news agency, Fides, denounced the move as a "violation of the freedom of conscience of Russian Catholics and of international accords."
Earlier this month, an Italian priest based in Russia was also refused re-entry, and told he was on a list of banned foreigners.
Most Catholic priests and bishops in Russia are from other countries, leaving them vulnerable as the Orthodox Church becomes increasingly vocal in its posture toward the Vatican.
Orthodox officials accuse the Catholic Church of trying to expand its influence in Russia and in neighboring Ukraine, where Catholics are trying to regain property seized during the Soviet era. Orthodox Patriarch Alexei II has long refused to agree to let Pope John Paul II visit Russia, although some Russian politicians have invited him.
Relations were further strained in February, when the Vatican elevated some apostolic regions in Russia to full dioceses. Orthodox leaders called it an "invasion" of their canonical territory.
There are about half-a-million Catholics among Russia's 145-million people. Many of them are of Polish, German or Ukrainian origin. The majority of Russia's population is Orthodox.