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

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

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

"Especially 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 last month's summit of the two leaders, the spokesman added, without elaborating on the timing. The pope has said he wants to visit Japan next year.

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 the pope is the first by a North Korean leader since 2000. Although that meeting, proposed by Kim's father, Kim Jong Il, never materialized, the plan for Francis to visit is the North's latest diplomatic initiative this year.

Kim held an unprecedented summit with U.S. President Donald Trump in Singapore in June, and pledged to work toward denuclearization 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 they turned the page on decades of public acrimony, 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 held three summits this year, following years of confrontation marked by the North's nuclear and missile tests.

Moon's Europe tour, scheduled for Oct. 13 to 21, is primarily to attend the Asia–Europe Meeting in Belgium and includes stops in France, Italy and Denmark, his office said.