Pope Francis urged the divided Koreas to unite as "one family, one people" in a spirit of mutual forgiveness at a mass Monday that coincided with a South Korea-US military drill condemned by the North as a prelude to war.
"Forgiveness is the door which leads to reconciliation", although it may seem "impossible, impractical and even at times repugnant", Francis said at a special mass for inter-Korean peace and reconciliation in Seoul.
"All Koreans are brothers and sisters, members of one family, one people," the pope said, as he wound up a five-day visit to South Korea.
The mass, in the capital's Myeongdong cathedral, was one of the most anticipated events of the visit, and South Korean President Park Geun-Hye was among the congregation.
The pope's message was cloaked in a religious context and he avoided any overt political statement, with no mention of the repressive level of control exerted by the regime in Pyongyang over all religious activity.
"Let us pray, then, for the emergence of new opportunities for dialogue, encounter and the resolution of differences," he said.
North Korea threat
The mass coincided with the launch of an annual South Korea-US military exercise involving tens of thousands of troops to test combat readiness for a North Korean invasion.
North Korea has repeatedly called for the exercise to be cancelled, and on Sunday its military joint chiefs of staff threatened to "mercilessly open the strongest... pre-emptive strike" if it goes ahead.
The Korean peninsula was divided in 1948 and the split was solidified by the 1950-53 Korean War, which concluded without a peace treaty leaving the two Koreas still technically at war.
Church officials in the South had sent several requests to Pyongyang to send a group of Catholics to attend Monday's mass, but the North declined the offer, citing its anger at the joint military drill.
At the very moment Pope Francis landed in South Korea at the start of his visit on Thursday, North Korea carried out a series of short-range rocket launches into the sea off its east coast.
Pyongyang later insisted it had no intention of upstaging the visit, and said the tests had been timed to coincide with the anniversary of Korea's liberation from Japanese colonial rule.
In his first public comments on arriving, the pope had stressed that peace on the divided peninsula could only be achieved through dialogue, "rather than ... displays of force".
The Catholic Church, like any other religion, is only allowed to operate in North Korea under extremely tight restrictions, and within the confines of the state-controlled Korean Catholics Association.
It has no hierarchical links with the Vatican and there are no known Catholic priests or nuns.
A recent report compiled by a UN Commission of Inquiry into human rights in North Korea concluded that practising Christianity outside the state-sanctioned church amounted to a "political crime".
"Today's mass is first and foremost a prayer for reconciliation in this Korean family," Francis said Monday.
"The cross of Christ reveals the power of God to bridge every division, to heal every wound, and to reestablish the original bonds of brotherly love," he added.