A large group of paintings has been discovered by archaeologists inside the ancient Church of Raphael in Northern Sudan.

The church, discovered in 2006, is located next to the relics of a medieval palace in Dongola, the capital of the once-powerful kingdom of Makuria, which existed from the sixth to the 14th century.

The largest group of paintings, from the turn of the fourteenth century, has been unearthed during excavations of the church by members of the  Centre of Mediterranean Archaeology of the University of Warsaw.

"The design is unique – it does not repeat the plans of other famous religious buildings of this type. Paintings are also unusual," Prof Wlodzimierz Godlewski, a long time researcher of Dongola, told Science and Scholarship in Poland.

The paintings depict archangels, angels, priests, saints and Nubian kingdom officials from the beginning of the ninth century, each with a legend describing the person and their function.

"It is the oldest example of the official iconography introduced into the sacred interior – we know a similar example from Faras, but it comes from a later period," Godlewski said.

An inscription on the wall of the baptistry has revealed new details about the King of Makuria and the city itself.

"The inscription commemorates the meeting of the bishops of Makuria with the king and archbishop of Dongola that took place in this church. This record revealed the territorial division of the church in Makuria – it listed the names of the bishops from particular towns,"Godlewski said.

"The church was founded by King Joannes. Until now we did not know much about him. The inscription proves that he was an important person in the hierarchy of the church and had considerable political influence."