(CNN) Pope Francis received an invitation Thursday from Kim Jong Un to visit North Korea, and said he would consider the invitation, according to a South Korean spokesman.

The offer was conveyed verbally by South Korean President Moon Jae-in during his visit to the Vatican, the spokesman said.

The invitation comes at a time when the North Korean leader is on a diplomatic outreach campaign, holding several summits in recent months with the leaders of South Korea and of China, and meeting with US President Donald Trump.

The Vatican declined to comment on whether the Pope would accept, but no pope has ever visited North Korea. North Korea's proposal could come under scrutiny because of the country's track record on religious tolerance.

"North Korea is the worst oppressor of religion," said Michael Green, a former National Security Council official now with the Center for Strategic & International Studies. "To physically travel to North Korea and meet with Kim, I fear, would legitimize a leader who is the greatest enemy to religious freedom on the face of the Earth."

Read More