The visit by Kim Jong-un's sister to the Republic of Korea for the Pyeongchang Winter Olympics shows unprecedented friendliness by the Democratic People's Republic of Korea toward its neighbor, an expert said.

Kim Yo-jong, 30, the younger sister of the DPRK top leader, will be part of a high-level delegation led by the DPRK's president of the Presidium of the Supreme People's Assembly Kim Yong-nam, the ROK's Unification Ministry said on Wednesday.

Seoul's presidential Blue House said the ROK welcomed the visit. Kim Euikyeom, the Blue House spokesman, told a news conference that the announcement shows Pyongyang's resolve to defuse tensions on the Korean Peninsula, according to the ROK's Yonhap News Agency.

Li Chengri, an expert at the Chinese Academy of Social Sciences, said Kim Yo-jong will be the first member of the Kim family ever to visit the ROK and will be making her debut at an international event.

"She is not only a senior member of the ruling party but also a family member of Kim Jong-un, this shows that the DPRK cherishes the Games and sees it as an important opportunity to improve relations," Li said.

It is highly possible that Kim Yo-jong will meet with ROK leader Moon Jae-in to express hopes for a successful Olympics as well as improve ties on behalf of Kim Jong-un, Li said.

Kim Yo-jong, the first vice-director of the ruling Workers' Party of Korea, was included in the delegation scheduled to make a three-day visit slated to begin on Friday, when the 2018 Winter Olympics holds the opening ceremony in the ROK's eastern county of Pyeongchang.

Also included in the DPRK delegation were Choe Hwi, chairman of the National Sports Guidance Committee, and Ri Son-gwon, chief of the Committee for the Peaceful Reunification of the Fatherland.

Meanwhile, a DPRK delegation of 280 members arrived in the ROK on Wednesday. Led by Sports Minister Kim Il-guk, it includes a 229-member cheer squad, four officials from the National Olympic Committee, 26 demonstrators of Taekwondo, a traditional Korean martial artist, and 21 journalists.

The Samjiyon orchestra will hold concerts on Thursday and Sunday to celebrate the Winter Olympics.

During the inter-Korean talks in January, the DPRK agreed to dispatch its athletes, cheerleaders and ranking officials to the ROK-hosted Winter Olympics.

Earlier this month the DPRK sent a 46-member delegation, including 22 athletes and a 140-member art troupe to the ROK.

Seoul and Pyongyang also agreed to march together under a unified Korean flag at the opening ceremony of the Winter Olympics and cheer together for both athletes.

Xinhua contributed to this story.