ANKARA: Turkey’s highest administrative court on Thursday began considering a request to turn Istanbul’s iconic Hagia Sophia, which now serves as a museum, back into a mosque.

The 6th-century structure was the Byzantine Empire’s main cathedral before it was changed into an imperial mosque following the Ottoman conquest of Istanbul. Mustafa Kemal Ataturk, the founder of the modern Turkish republic, then turned into a museum that attracts millions of tourists each year.

Nationalist and religious groups have long been pressing for the structure, which they regard as an Muslim Ottoman legacy, to be converted back into a mosque. Others believe the UNESCO World Heritage site should remain a museum, as a symbol of Christian and Muslim solidarity.

On Thursday, Turkey’s Council of State, heard arguments by lawyers for a group devoted to reverting Hagia Sophia back into a mosque, the private HaberTurk television reported. The group is pressing for an annulment of the 1934 decision by the Council of Ministers that turned the historic structure into a museum.

A court counsel recommended that the request be rejected, arguing that a decision on restoring the structure's Islamic heritage was up to the government, the station reported.

A decision is expected within two weeks.

Greece as well as the Istanbul-based Ecumenical Patriarch Bartholomew I, considered the spiritual leader of the world’s Orthodox Christians, have urged Turkey to keep Hagia Sophia as a museum. Bartholomew warned this week that its conversion into a mosque “will turn millions of Christians across the world against Islam.”

U.S. State Secretary Mike Pompeo waded into the debate Wednesday, urging Turkey to keep Hagia Sophia as a museum “to serve humanity as a much-needed bridge between those of differing faith traditions and cultures.” His comments sparked a rebuke from Turkey’s Foreign Ministry, which said Hagia Sophia was a domestic issue of Turkish national sovereignty.

Built under Byzantine Emperor Justinian, Hagia Sophia was the main seat of the Eastern Orthodox church for centuries, where emperors were crowned amidst ornate marble and mosaic decorations.

Four minarets were added to the terracotta-hued structure with cascading domes and the building was turned into an imperial mosque following the 1453 Ottoman conquest of Constantinople — the city that is now Istanbul.

The building opened its doors as a museum in 1935, a year after the Council of Ministers’ decision.