Pope Francis has asked for an invitation from North Korea to visit the isolated country, South Korean broadcaster KBS reported.

"I will go there as soon as they invite me. I'm saying they should invite me. I will not refuse," KBS quoted the pope as saying in an interview aired on Thursday.

Such a visit would be the first by a pope to the reclusive state, which does not allow priests to be permanently stationed there. Little is known about how many of its citizens are Catholic, or how they practice their faith.

Former South Korean President Moon Jae-in, who is Catholic, has urged Francis to visit North Korea, saying a papal visit to Pyongyang would help build peace on the Korean peninsula.

When he met the pope in 2018, Moon relayed a verbal invitation to Francis from North Korean leader Kim Jong Un. The Vatican is still waiting for a written invitation.

At the time, Vatican officials said the pope, who has made many appeals for rapprochement between the two Koreas, could consider such a trip under certain conditions if it could help the cause of peace.

Last year, Moon met the pope again and gave him a cross made out of barbed wire from the demilitarized zone that divides the two sides. He again urged the pope to visit the north.

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 - including a Catholic church in the capital, Pyongyang - no open religious activity is allowed and the authorities have repeatedly jailed foreign missionaries.