ISTANBUL (Reuters) - Turkey’s President Tayyip Erdogan said on Friday Istanbul’s Hagia Sophia should be re-titled as a mosque instead of a museum after Sunday’s elections, but did not say whether the status of the landmark site would be changed.

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Hagia Sophia, a UNESCO World Heritage Site, was the foremost cathedral in Christendom for 900 years before becoming one of Islam’s greatest mosques for 500 years until 1935, when it was converted to a museum.

In 2014, amid rumors of a possible change, senior Erdogan adviser Ibrahim Kalin said there were no plans to alter the monument’s status.

In the lead-up to local elections on Sunday, Erdogan has appealed to religious sentiments to drum up support for his party, invoking the New Zealand mosque killings as examples of the threats faced by Turkey, and Islam.

He has also brought up the issue of Hagia Sophia several times.

“After elections, we will change Hagia Sophia’s name from museum to mosque,” he told a crowd in Istanbul at an election rally on Friday. “We have some plans and we are going to implement these plans.”

He did not expand on what those plans are.

On Thursday, the United States Commission on International Religious Freedom (USCIRF) condemned Erdogan’s comments earlier this week on the museum.

"Hagia Sophia bears profound historical and spiritual significance to Muslims and Christians alike, and its status as a museum must be maintained," USCIRF Chair said in a statement here.

“President Erdogan’s comments are needlessly provocative and hurtful to Turkey’s minority religious communities. Additionally, the implications of such an action are compounded by the deteriorating landscape for religious freedom, democracy and human rights in Turkey.”