Moon's meeting with the pope will be "exceptional," according to the Vatican, as the pope usually receives a visiting foreign head of state early in the morning and usually only for about half an hour.

Seoul's presidential office Cheong Wa Dae has said the president will deliver an invitation from North Korean leader Kim Jong-un for the pontiff to visit the North.

Moon visited Pyongyang last month for his third inter-Korean summit with Kim.

Many believe the pope's trip to Pyongyang, if made, may help motivate the communist state to further accelerate its denuclearization process as it could offer global recognition of the North as a normal state.

No pope has ever visited the communist state.

The South Korean president will head for Brussels later in the day, wrapping up his three-day official visit to Rome and the Vatican.

He is currently on a five-nation tour that began in Paris and will end in Denmark. (Yonhap)