Germany has commented on Turkey's decision to convert Hagia Sophia into a mosque, RIA Novosti reported.

According to German Chancellor Angela Merkel's spokesperson Steffen Seibert, Berlin regrets this decision.

Hagia Sophia has great cultural and historical significance, and it has great religious significance for both Christianity and Islam, he added.

Turkish President Recep Tayyip Erdogan signed a decree Friday on converting Hagia Sophia into a mosque.

Erdogan tweeted a copy of the decree he had signed according to which the decision had been taken to hand control of 'the Ayasofya Mosque, as it is known in Turkish, to the country’s religious directorate and reopen it for worship.'

Thus, a Turkish top administrative court annulled a 1934 presidential decree converting Hagia Sophia into a museum.

The Hagia Sophia was the Roman Empire's first Christian cathedral: it was converted from a Greek Orthodox cathedral to a mosque in 1453 and then became a museum in 1935.

The site is inscribed as a UNESCO World Heritage site.