Pope Francis has said he’s “pained” by Turkey’s decision to convert Istanbul’s Hagia Sophia back into a mosque.

Speaking at a service in the Vatican, the Roman Catholic leader added that his “thoughts go to Istanbul”.

Hagia Sophia was built as a Christian cathedral nearly 1,500 years ago and turned into a mosque after the Ottoman conquest of 1453.

The Unesco World Heritage Site became a museum in 1934 under Turkish Republic founding father Ataturk.

But earlier this week a Turkish court annulled the site’s museum status, saying its use as anything other than a mosque was “not possible legally”.

Islamists in Turkey have long called for it to become a mosque again but secular opposition members opposed the move.

Several religious and political leaders worldwide have criticised the move.

The World Council of Churches has called on President Erdogan to reverse the decision. The Church in Russia, home to the world’s largest Orthodox Christian community, immediately expressed regret that the Turkish court had not taken its concerns into account when ruling on Hagia Sophia.