Russian officials and the Russian Orthodox Church have urged Turkey to be cautious about efforts to return the Hagia Sophia Museum in Istanbul to a mosque, as it has "sacred value" for the Russians.
The State Council, which is the highest administrative court in Turkey, is looking into this issue and the ruling may be issued within days, in a move that could raise tensions with the West and the Christian community.
The head of the Orthodox Church, Patriarch Kirill in Russia, expressed his "deep concern" to reflect on the move, describing Hagia Sophia as "one of the greatest traces of Christian heritage."
He said in a statement that "any threat that surrounds Hagia Sophia is a threat to the entire Christian civilization, and therefore to our spiritual values and history."
He added that, for every Russian Orthodox person, the Hagia Sophia is a tourist attraction, calling on the Turkish authorities to exercise caution.
He noted that changing the current "neutral status" of the historic building, would cause "deep pain" for the Russian people.
For his part, Kremlin spokesman Dmitry Peskov said that the future of the historical site is an internal Turkish issue, but he hoped that the Hagia Sophia status would be taken into consideration as a world heritage site.
He explained that the former cathedral was "unique" and had "sacred value" for the Russians.
The Church of Hagia Sophia was converted into a mosque with the Ottomans conquering Constantinople in 1453, then it became a museum in 1935 at the hands of Turkish President Mustafa Kemal Ataturk, with the aim of "dedicating it to humanity."
And Turkish President Recep Tayyip Erdogan has previously proposed returning the UNESCO World Heritage Site to a mosque again.
Erdogan last week described criticism of a possible diversion of this historical impact as an attack on Turkish sovereignty.