ANKARA, Turkey — The Greek Orthodox Church of the United States said Tuesday it is petitioning United Nations experts to coerce Turkey into protecting Orthodox Christianity's cultural heritage following the Turkish government's conversion of Istanbul's landmark Hagia Sophia from a museum into a mosque.

The Greek Orthodox Archdiocese of America said it was pressing U.N. special rapporteurs in the areas of cultural rights, minority rights, freedom of religion and beliefs to hold Turkey accountable "for its deliberate policies to erase the cultural heritage of Orthodox Christians."

In a move that drew praise from the Muslim faithful and widespread international opposition, Turkish President Recep Tayyip Erdogan issued a decree in July that turned Hagia Sophia back into a Muslim house of prayer. The structure, a UNESCO world heritage site, had served as one of Christendom most important cathedrals and a mosque for centuries, as well as a museum for 86 years.

Erdogan announced a decision last month to transform the Church of the Holy Saviour in Chora, another Byzantine-era church in Istanbul, into a mosque as well.

"By unilaterally changing the status, structure and name of these UNESCO sites, with particular significance to Orthodox Christians, Turkey is in violation of its obligations under international law to preserve cultural heritage and to respect the political, cultural and religious freedoms of Orthodox Christians in Turkey and abroad," Archdiocese of America counsel Christina Hioureas told The Associated Press in an emailed statement.

– including UNESCO, and its member states will motivate Turkey to reverse its decision to convert (the world heritage sites) into mosques."

There was no immediate comment from the Turkish government, which has vowed to protect Hagia Sophia and to keep it open to visitors outside of prayer hours.

Built by the Byzantine Emperor Justinian in 537, Hagia Sophia was turned into a mosque with the 1453 Ottoman conquest of Istanbul. Mustafa Kemal Ataturk, the founding leader of the secular Turkish republic converted the structure into a museum in 1934.

Erdogan, a pious Muslim whose ruling party has roots in Turkey's Islamic movement, re-converted the building into a mosque despite calls for it to be kept as a museum in recognition of Istanbul's multi-faith heritage.

The move was largely seen as being geared toward consolidating the ruling party's conservative and religious support base at a time when its popularity is sagging amid an economic downturn.

"The Hagia Sophia was built 15-hundred years ago to be the cathedral and first church of the Ecumenical Patriarchate," Greek Orthodox Archbishop Elpidophoros of America said.

"Today, with a heavy heart, we behold the historic and indeed essential Greek Orthodox Christian cultural heritage of Turkey being misappropriated, with the conversion of Hagia Sophia into a mosque," he told the AP. " To do so is to start down a path toward denial of history, a path that denies the future as well."