The invitation to visit Pyongyang will be delivered by South Korean president Moon Jae-in who will be in the Vatican next week as part of a trip to Europe.

No pope has ever visited North Korea, though the late Pope John Paul II was once invited.

North Korea and the Vatican have no formal diplomatic relations.

"During the meeting with Pope Francis, [Mr Moon] will relay the message from chairman Kim Jong-un that he would ardently welcome the Pope if he visits [the North Korean capital] Pyongyang," Mr Moon's spokesman, Kim Eui-kyeom, told reporters.

The invitation is the latest reconciliatory gesture from North Korea.

Mr Kim held an unprecedented summit with US President Donald Trump earlier this year and three inter-Korean summits also took place.

Mr Trump and Mr Kim became the first sitting US president and North Korean leader to meet

In 2000, Kim Jong-un's father - Kim Jong-il - invited Pope John Paul II to visit North Korea after the pope was quoted as saying it would be "a miracle" if he could go there.

That invitation came at a summit with the then South Korean President, Kim Dae-jung. The visit never happened.

According to news wire the Associated Press, the Vatican insisted at the time that a visit from the pope would only happen if Catholic priests were accepted in North Korea.

Does the North have religious freedom?

North Korea's constitution promises a "right to faith" and state-controlled churches do exist. However, one human rights activist say this is all largely for show.

"In reality, there is no freedom of religion," said Arnold Fang, a researcher from Amnesty International.

A 2014 UN report found Christians faced "persecution and severe punishments" if they practiced their religion outside state-controlled churches.

According to news site NK News, North Korea does maintain a Catholic church in Pyongyang - the Jangchung Catholic Church - though it is not officially affiliated with the Vatican.

A state-run Korean Catholic Association also exists but, similarly, has no ties with the Vatican. According to news wire AFP, KCA estimates there are 3,000 Catholics in the country, while the UN puts the number at around 800.

North Korea also takes a dim view of foreign missionaries.

Kenneth Bae, a Korean-American evangelist who ran Christian tours of North Korea, was sentenced to 15 years of hard labour in 2013 for "anti-government" crimes. He was released in 2014 on health grounds.