ISTANBUL (Reuters) - Mosaics depicting Christian figures in Istanbul’s ancient Hagia Sophia will be covered with curtains during Muslim prayers, Turkish presidential spokesman Ibrahim Kalin said on Sunday, as work to prepare the building for use as a mosque continues.

Authorities had said last week that the mosaics would be concealed with either curtains or lasers when the first prayers are held next Friday.

In a move that sparked sparked international criticism and concern, President Tayyip Erdogan declared Hagia Sophia open to Muslim worship earlier this month following a court ruling that said the building’s conversion to a museum in 1934 was unlawful.

Hagia Sophia dates back to the sixth century and has a history as both a church and a mosque before it was turned into a museum.

In an interview with broadcaster NTV, Kalin said some mosaics of Mary and Gabriel that are positioned in the direction of Qiblah, where Muslims face during prayer, would be covered with curtains.

He said other mosaics of Jesus and other Christian figures did not pose an obstacle for Muslim prayers because they are not located in the direction of Qiblah. But he did not say whether they would remain uncovered at all times.

Outside prayers, Hagia Sophia will be open to all visitors and tourists and all mosaics will be uncovered, authorities have said.

Erdogan visited the mosque earlier on Sunday to inspect the progress in preparing the building.