An underground church containing frescoes that may date back to the 12th century has been discovered in the Cappadocia region of Turkey.

The church was found during excavations for an urban housing project in the central Anatolian province of Nevşehir and local authorities say it could become a major Christian pilgrimage site.

According to Nevşehir's mayor, Hasan Ünver, the frescoes depict the Ascension and the Last Judgment.

"We know that such frescoes have so far never been seen in any other church," he said, adding that preliminary studies show the church might date back to the 5th century AD.

The church is part of a complex of dwellings and other structures created in the soft rock of the area, close to the UNESCO World Heritage Site of Cappadocia. The underground city, discovered in 2014, is thought to be the largest in the world and was first inhabited around 5,000 years ago. Tunnels up to 7 kilometres long have been discovered. 

Some frescoes in the church have been damaged but archaeologists believe they can be restored.

The church has only been partially excavated. So far just the ceiling has been seen and the height of the structure is not known. Archaeologist Ali Aydin told the Hurriyet Daily News that work had stopped until the Spring in order to protect the paintings from the winter humidity.

He said: "Only a few of the paintings have been revealed. Others will emerge when the earth is removed. There are important paintings in the front part of the church showing the crucifixion of Jesus and his ascension to heaven. There are also frescoes showing the apostles, the saints and other prophets Moses and Elyesa [Elijah]."

The newly-discovered church is one of many created in the region, some of them dating back to the earliest Christian centuries; the open-air museum at nearby Goreme is a popular tourist destination.

The area is also famous for producing some of the early Church's greatest theologians. The Cappadocian Fathers – Basil the Great, Gregory of Nyssa and Gregory Nazianzen – developed the doctrine of the Trinity and are revered in the Eastern and Western Churches.