Pope Francis could make a short day trip to Scotland in September, it has been claimed.

It's understood the pontiff has pencilled in a trip to coincide with the signing of a charter which would call on all faiths to unite against extremism.

Mario Aguilar, an academic at St Andrews University, has invited Francis to the unveiling of the charter in September.

He said he had received a response from the Vatican indicating the pope was interested in attending.

"My understanding is that Pope Francis is interested and has put [the event] on his agenda of activities and that further arrangements will be discussed," he told the Sunday Times.

The event has the support of Archbishop Desmond Tutu and the Dalai Lama.

Any visit is expected to be short and only last a day.

The Vatican did not comment.