North Korea has endorsed leader Kim Jong-un as the general secretary of the ruling Workers' Party at its ongoing congress, state media said Monday, in an apparent move to tighten his grip on power.

The election took place at the sixth-day session of the party's eighth congress in Pyongyang on Sunday, following the North's revision of party rules to reinstate the secretariat system that was scrapped in 2016, according to the North's official Korean Central News Agency (KCNA).

"The 8th Congress ... unanimously adopted a decision on electing Kim Jong-un as general secretary of the Workers' Party of Korea in reflection of the unanimous will and desire of all the delegates and other Party members, all the people and service personnel of the People's Army," the report said.

The general secretary title was previously held by Kim's late predecessors, his grandfather Kim Il-sung and father Kim Jong-il.

Since Kim took office following his father's death in late 2011, the North has called Kim Jong-il the "eternal general secretary" of the party and Kim Il-sung the "eternal president" of North Korea.

During an election that took place the same day, Kim's younger sister, Kim Yo-jong, was not included as an alternate member of the party's powerful political bureau.

Speculation has swirled that the younger Kim, previously an alternate member of the politburo, could be promoted to a higher position as she appeared to have undertaken a prominent role in inter-Korean affairs and other key issues.

Yet experts say it is too early to say if Kim Yo-jong's position has weakened, as she could continue to play an important role in state affairs as the only sister of the leader, regardless of her title.

Jo Yong-won, a senior party official who was often spotted accompanying the leader during his field trips last year, was promoted to a member of the presidium of the political bureau, a position held by only five people in the North including leader Kim.

Pak Pong-ju, a former member of the presidium, was removed from all party positions apparently due to his age as a shift in generations was witnessed across major party posts.

The position of key officials involved in relations with the United States and inter-Korean affairs appears to have weakened at the party congress, according to experts.

North Korea's First Vice Foreign Minister Choe Son-hui was demoted to an alternate member of the party's central committee from a member amid an impasse in the North's nuclear negotiations with the United States.

Foreign Minister Ri Son-gwon maintained his position as an alternate member of the political bureau, dismissing earlier speculations that he has been removed from the key party position.

Ri, however, was the last official to be called upon at the party congress among the appointed alternate members.

"Considering the very low status given to the elite in diplomatic and inter-Korean affairs, Kim Jong-un is likely to concentrate more on domestic issues than on diplomatic or inter-Korean ties at least until the COVID-19 crisis eases," Cheong Seong-chang, a senior researcher at the Sejong Institute, said.

The North Korean leader has held three meetings with US President Donald Trump, but denuclearization talks have made little progress since their no-deal summit in Hanoi in February 2019.

During an earlier session of the congress, Kim defined the US as the North's "foremost principal enemy" and vowed to bolster its nuclear arsenal, which experts see as aimed at pressuring the incoming Joe Biden administration.

Jang Kum-chol, head of the North's United Front Department (UFD) that deals with inter-Korean affairs, also has been replaced with Kim Yong-chol amid chilled cross-border ties.

Kim Yong-chol, who previously served as the head of the UFD, lost his position after the breakdown of the Hanoi summit, and had served as vice chairman of the party committee.

Kim was excluded from the list of the party's secretaries after the secretariat system was revived, which is considered a demotion from his position as a vice chairman.

The North also appears to have removed the position of secretary of inter-Korean affairs.

According to Yang Moo-jin, a professor at the University of North Korean Studies, the removal of the post could signal "the weakening of inter-Korean affairs." He also pointed to the possibility that Kim Yo-jong, the leader's sister, could fill the position.

Meanwhile, Kim Song-nam, first vice director handling relations with China, was promoted to director.

On the military front, Kwon Yong-jin was promoted to the director of the General Political Bureau of the North Korean Army, while Kim Jong-gwan was named the defense minister. North Korea earlier renamed the Ministry of People's Armed Forces as the defense ministry, a step widely seen as an effort to fit into the image as a "normal state."

Experts say the North's leader is now expected to boost his new leadership style in full swing while inheriting the history and tradition of his predecessors.

"Yet diplomacy with the US and economic recovery remain the biggest challenges for North Korea, and without properly resolving these tasks, it will be difficult for Kim to secure his authority as the general secretary," Lim Eul-chul, a professor at the Institute for Far Eastern Studies at Kyungnam University, said.

North Korea has faced a triple whammy of the fallout of back-to-back typhoons in summer, a protracted border closure due to the coronavirus pandemic, and global sanctions on its economy.

On Monday, President Moon Jae-in vowed to make a "last-ditch effort" to pull off a "great transition" in the stalled dialogue, saying South Korea is ready to talk with the North "anytime, anywhere, even in a non-face-to-face formula."

KCNA said the congress, which began Tuesday, was to continue with a seventh-day session.

The event appears to be coming to an end, but it is unclear exactly when the congress will close as the North has not made public the schedule. The previous congress in 2016 was held for four days.

South Korea's military said it has detected signs indicating that the North carried out a military parade in Pyongyang late Sunday. It would be the first such event since a massive military parade was staged in October to celebrate the party's 75th founding anniversary. (Yonhap)