SEOUL (Reuters) - North Korea’s delegation sent to the Winter Olympics held “frank and candid” talks with South Korean President Moon Jae-in, the North Korean news agency said on Sunday, but it made no mention of the North’s invitation to Moon to Pyongyang for a summit.

South Korean President Moon Jae-in shakes hands with Kim Yo Jong, the sister of North Korea's leader Kim Jong Un, in Seoul, South Korea in this undated photo released by North Korea's Korean Central News Agency (KCNA) February 10, 2018. KCNA/via REUTERS

The delegation, the highest-ranking to visit the South and led by the younger sister of the North’s leader Kim Jong Un, concluded its visit on Sunday after charming and intriguing the South Korean public, but still faces deep scepticism over Pyongyang’s sincerity towards improving relations.

Any summit between the two still-officially warring Koreas would be a coup for Moon, who has been pushing for a diplomatic solution to the standoff over North Korea’s nuclear and missile programs.

In a rare honor for visiting foreign guests, Moon met Kim’s sister, Kim Yo Jong, four times during the delegation’s three-day visit. Moon’s chief of staff held a farewell dinner for the delegation before the delegation attended a performance by a North Korean orchestra, the last item on their itinerary before heading home.

“I never thought I would visit (the South) so suddenly and believed much would be strange and different but I saw many things that were similar or the same,” said Kim Yo Jong in a toast during Sunday’s dinner, adding she hoped to meet the “friendly faces” before her later in Pyongyang.

Earlier South Korean Prime Minister Lee Nak-yeon had hosted a lunch for the Pyongyang delegation at a five-star hotel.

On Saturday Kim Yo Jong “courteously” handed over a personal letter from the North Korean leader to Moon and told him of her brother’s “intention”, North Korea’s state news agency KCNA said, without elaborating what that was.

South Korean officials said Moon had been invited to Pyongyang to speak with Kim Jong Un during the talks and lunch that Moon hosted at the presidential Blue House in Seoul on Saturday.

Such a meeting, if it came about, would mark the first inter-Korea summit since 2007.

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U.S. Vice President Mike Pence, back in Washington after attending the opening of the Winter Olympics in Pyeongchang, said the United States, South Korea and Japan were in complete agreement on isolating North Korea over its nuclear weapons program.

“There is no daylight between the United States, the Republic of Korea and Japan on the need to continue to isolate North Korea economically and diplomatically until they abandon their nuclear and ballistic missile program,” Pence told reporters during the return flight to the United States.

A White House official said although Moon did not discuss the invitation with Pence, the South Korean president made it very clear that only when North Korea actually starts to take steps to denuclearise would anyone even consider beginning to take the pressure off.

‘COME VISIT PYONGYANG’

Loud applause greeted the appearance of Moon, Kim Yo Jong and her delegation at the concert, attended by more than a thousand people. The North Korean orchestra will return home on Monday after their second and last performance on Sunday.

North Korea’s nominal head of state, Kim Yong Nam, a member of the delegation, was seen wiping away tears with his handkerchief and at times clapping enthusiastically during the show.

“Always stay healthy and please come and visit Pyongyang with President Moon,” Kim Yo Jong told South Korea’s First Lady Kim Jung-sook after the show ended.

The North’s high-level delegation returned to Pyongyang from Incheon International Airport via private jet, just as they had arrived on Friday.

According to the Blue House, Kim Jong Un wanted to meet Moon “in the near future” and would like him to visit North Korea “at his earliest convenience”, his sister told Moon.

Blue House spokesman Kim Eui-kyeom cited Moon as replying: “Let’s create the environment for that to be able to happen.”

During Sunday’s lunch at the Walkerhill Hotel, Prime Minister Lee told the North Korean delegation he hoped the “right conditions” would be created for the two heads of state to meet, an official from Lee’s office said.

Sunday’s KCNA report cited Moon as saying inter-Korean relations should be mended by the parties concerned “at any cost as indicated by Chairman Kim Jong Un in his New Year Address”.

Kim Yong Nam, the North’s ceremonial president, said “even unexpected difficulties and ordeals could be surely overcome and the future of reunification brought earlier when having a firm will and taking courage and determination to usher in a new heyday of inter-Korean relations”.

However, South Korea’s main opposition party warned that any talks between the two Koreas where the scrapping of North Korea’s nuclear program was not a precondition would only “benefit the enemy”.

“We should firmly keep in mind that any talks where denuclearisation is not a precondition only buy North Korea more time to complete its nuclear capabilities while they fool us with their peace offensive façade,” said Chang Je-won, spokesman for the Liberty Korea Party.

Japanese editorials sounded a similar warning, saying dialogue would be meaningless unless it led to denuclearisation of the Korean peninsula.