ISTANBUL (AFP) – Turkey’s top court on Thursday turned down a plea to open the Hagia Sofia, an Istanbul landmark that is now a museum after serving as both a church and a mosque over its long history, for Muslim worshipping.

The Constitutional Court rejected an association’s demand that the Hagia Sophia be opened for Muslim prayers on “non-competence” grounds, indicating it was not the proper instance to allow any change, the official Anadolu news agency reported.

In its plea, the association had claimed that barring prayers at Hagia Sophia was breaching the right to freedom of expression and conscience.

The Haberturk website said that the demand had come from an independent Turkish heritage association.

The Hagia Sophia was turned into a museum accessible to all by the secular founders of modern Turkey in the 1930s. Secular Turks are wary of any moves to re-Islamise the building or have it reconsecrated as a mosque.

There has in recent years under the rule of President Recep Tayyip Erdogan been an increase in Muslim activity inside the museum, with Koran readings taking place on occasion.

The Hagia Sophia was constructed in the sixth century as a church in the Christian Byzantine Empire and was the seat of the Patriarchate of Constantinople, Istanbul’s former name.

When Ottoman forces under Sultan Mehmet II conquered the city in 1453 he ordered the immediate conversion of the Hagia Sophia into a mosque. Islamic minarets were built around its Byzantine dome.

It served as a mosque until after the collapse of the Ottoman Empire when in the mid-1930s the authorities of the new Turkish state under its secular founding father Mustafa Kemal Ataturk ordered it to become a museum for all.

Neighbouring Greece, which keeps a close eye on the state of Byzantine heritage in Istanbul, has occasionally expressed concern that the Hagia Sophia’s status as a secular museum could be under threat.