Pope Francis reacts to the idea of turning the Temple of Saint Sophia into a mosque 2:06
(CNN) - Pope Francis was silent for several minutes in his weekly Angelus prayer on Sunday, after he spoke about Turkey's decision to turn Hagia Sophia into a mosque.
"The sea takes my thought a little further, to Istanbul," said the pontiff during the prayer, which commemorates the people who work at sea.
"I think of Hagia Sophia, and I am very sad."
With a cabinet decree in 1934 the iconic building in Istanbul has served as a museum, but on Friday Turkish President Recep Tayyip Erdogan issued a presidential decree to transfer the administration of the Ministry of Culture building to the Presidency for Religious Affairs.
The decree follows an earlier ruling by a Turkish court that overturned the cabinet decree decades ago.
Hagia Sophia is a UNESCO World Heritage site, and the group says it deeply regrets Turkey's decision.
"Hagia Sophia is an architectural masterpiece and a unique testament to the interactions between Europe and Asia over the centuries," said Director General Audrey Azoulay.
"Its status as a museum reflects the universal nature of its heritage and makes it a powerful symbol for dialogue."
Greece and France have also questioned Turkey's secularism.
The history of the architectural jewel dates back to the Byzantine Empire in the 6th century, when it was built as a cathedral. In the 15th century, it was converted into a mosque.
Since Islam prohibits displaying images of people in mosques, officials plan to use lights and curtains to cover the numerous Byzantine Christian mosaics in Hagia Sophia, Turkey's chief of religious affairs Ali Erbaş said on Turkish television on Sunday.
After the prayer, the paintings will be discovered for visitors once again. Entrance fees will also be canceled, President Erdogan said.
"Like all our mosques, its doors will be open to everyone, Muslim or non-Muslim," said Erdogan.
"As a common heritage of the world, Hagia Sophia, with its new status, will continue to embrace everyone in a more sincere way."
CNN's Sharif Paget, Murat Baykara, Isil Sariyuce, Livia Borghese and Zahid Mahmood contributed to this report.