Turkish President Recep Tayyip Erdogan on Sunday mooted the possibility of renaming Istanbul's Hagia Sofia museum as a mosque, in comments during a television interview.
Asked whether the entrance fee to the city landmark might be waived, he said: "It's not impossible... but we would not do it under the name 'museum' but 'Hagia Sophia mosque'."
He added: "Tourists come and go at the Blue Mosque. Do they pay anything? ... Well, we will do the same with the Hagia Sofia."
Erdogan, who is a former mayor of Istanbul, is campaigning for votes for his Justice and Development Party (AKP) ahead of municipal elections on March 31.
The former church and mosque, now a museum, often sparks tensions between Christians and Muslims over Islamic activities held there including the reading of verses from the Koran or collective prayers.
Its secular status allows believers of all faiths to meditate, reflect or simply enjoy its astonishing architecture.
But calls for it to serve again as a mosque have caused anger among Christians and raised tensions between historic foes Turkey and Greece, both NATO members.
Greek Prime Minister Alexis Tsipras visited the Hagia Sophia in February. "You can feel the burden of history here," he told AFP.
Greece has repeatedly expressed concern over efforts to change the museum's status.
But Erdogan raised the issue again after the March 15 shootings in two mosques in Christchurch, New Zealand, that killed 50 people.
In speeches he has denounced a passage in the gunman's "manifesto" in which he said the Hagia Sophia would be "liberated" of its minarets.
The Hagia Sophia was first built as a church in the sixth century under the Christian Byzantine Empire as the centrepiece of its capital Constantinople, today's Istanbul.
Almost immediately after the conquest of Constantinople by the Muslim Ottomans in 1453, it was converted into a mosque before becoming a secular museum in a key reform of the new post-Ottoman Turkish authorities under Mustafa Kemal Ataturk in the 1930s.
Ataturk was the founder of the Turkish republic.
Since Erdogan's AKP came to power, critics and advocates of secularism fear the government harbours a hidden agenda to reconvert the Hagia Sophia into a mosque.
But Turkey's top court in September last year rejected an association's demand that the Hagia Sophia be opened for Muslim prayers.
The museum, a UNESCO World Heritage site, receives millions of visitors every year.