Pope Francis said dialogue and not "displays of force" would bring peace to the divided Korean peninsula as he began a visit Thursday to South Korea that the nuclear-armed North marked with a series of rocket launches.

In a speech to President Park Geun-Hye and senior officials and diplomats in Seoul, Francis said the quest for inter-Korean reconciliation was one that had implications for "the stability of the entire area and indeed of the whole war-weary world".

Acknowledging the relentless challenge of breaking down walls of "distrust and hatred", Francis voiced his appreciation of peaceful efforts to bring stability to the Korean peninsula.

"Diplomacy... is based on the firm and persevering conviction that peace can be won through quiet listening and dialogue, rather than by mutual recriminations, fruitless criticisms and displays of force," he said.

During his speech, Francis only referred to "Korea" or the "Korean peninsula" avoiding any specific mention of either the North or South, which have remained divided since the 1950-53 Korea War.

Minutes before the pope touched down at the start of his five-day visit, North Korea fired three short-range rockets into the East Sea (Sea of Japan, followed by two more later in the day.

"It is quite unseemly to fire such weapons on the day of the arrival of the pope, who comes here to give his blessing to all the people in the Korean peninsula, whether in the South or the North," said a foreign ministry spokesman in Seoul.

Speaking before the pope, President Park said his visit would help open an era of "Hope and reunification, and promised to expand humanitarian programmes to the North.

But she also stressed there could be no real progress until Pyongyang abandoned its nuclear weapons programme.

- Special 'reconciliation' mass -

The pope is expected to send a message of peace to Pyongyang when he conducts a special inter-Korean "reconciliation" mass in Seoul next week on the last day of his visit.

Church officials in the South had sent several requests to Pyongyang to send a group of Catholics to attend the event, but the North declined the offer, citing its anger at upcoming South Korea-US military drills.

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.

Earlier Thursday, North Korea had warned that if South Korea failed to cancel an upcoming military drill with the United States it would push the two sides "to the brink of war".

The annual Ulchi-Freedom Guardian exercise, which tests combat readiness for a North Korean invasion, is scheduled to begin the same day as the pope's reconciliation mass.

The pope's speech also touched on the social challenges facing Asian countries like South Korea that have been transformed by rapid economic development.

"In an increasingly globalised world, our understanding of the common good, of progress and development, must ultimately be in human and not merely economic terms," he said, stressing the importance of caring for the poor, the vulnerable and "those who have no voice."