North Korean leader Kim Jong Un has invited Pope Francis to visit Pyongyang, a gesture designed to highlight peace efforts, South Korea's presidential office said on Tuesday.

South Korean President Moon Jae-in will deliver Kim's invitation when he meets Francis next week during a trip to Europe, spokesman Kim Eui-kyeom said. North Korea and the Vatican have no diplomatic relations.

'President Moon will visit the Vatican on October 17 and 18 to reaffirm its blessing and support for peace and stability of the Korean peninsula,' the spokesman told a news briefing.

'When he meets with Pope Francis, he will convey Chairman Kim's message that he will ardently welcome him if he visits Pyongyang.'

Kim told Moon of his wish to meet the pope during a meeting last month, the spokesman added, without elaborating on the possible timing. The pope has said he wants to visit Japan next year.

The Vatican said in a statement that the pope will receive Moon at noon on October 17.

The day before, in St Peter's Basilica, Cardinal Pietro Parolin, the Vatican secretary of state and the pope's second-in-command, will say a 'Mass for Peace' on the Korean peninsula. Moon will attend the mass, the Vatican said.

North Korea's constitution guarantees freedom of religion as long as it does not undermine the state, but beyond a handful of state-controlled places of worship, no open religious activity is allowed.

The invitation to a pope is the first by a North Korean leader since Kim's father, Kim Jong Il, invited Pope John Paul in 2000, a trip that never happened.

Asked about the possibility of a trip, a Vatican spokesman said: 'Let's wait for the invitation to arrive.'

North Korea, which Church officials estimated had a Catholic community of about 55,000 just before the 1950-53 Korean War, does not allow priests to be permanently stationed in the country.

'Priests from the South occasionally visit, usually accompanying aid deliveries or humanitarian projects.

Information about how many Catholic are still in North Korea is scarce. Religious agencies have said they number in the few hundreds to about 4,000.

Kim held an unprecedented summit with US President Donald Trump in Singapore in June, and pledged to work toward denuclearisation of the Korean peninsula.

While Kim's actions since have fallen short of Washington's demands, the Trump administration is preparing for a second summit.

Before the detente, the leaders regularly traded threats and insults as North Korea pushed to develop a nuclear missile capable of hitting the United States. The two Koreas have held three summits this year.

On his European tour, scheduled for October 13 to 21, Moon will attend an Asia–Europe Meeting in Belgium, as well as France, Italy and Denmark, his office said.