North Korean leader Kim Jong-un called for strengthening the country's nuclear capabilities as he addressed the final-day session of the ruling party's rare congress, state media said Wednesday.

North Korea on Tuesday wrapped up the eighth congress of the Workers' Party, which had been held for more than a week since its opening on Jan. 5, according to the Korean Central News Agency (KCNA).

"While further strengthening our nuclear war deterrent, we need to do everything to build the strongest military capabilities," Kim said. "By accelerating the push to make our military more elite and strong, we need to have them thoroughly prepared to play their role against any form of threats or unexpected situations."

On the economy, the North Korean leader called for a more "desperate struggle" to fulfill a new five-year development plan put forth during the party congress.

"The future of our socialist achievement depends on how we carry forward the decisions made at this congress including the five-year plan for national economic development," he said.

Kim also expressed gratitude for electing him as general secretary of the party, saying "he hardly repressed his grateful and heavy feelings while receiving the greatest honor."

On Sunday, North Korea "unanimously" elected Kim as general secretary in a move further cementing his grip on power. The title was previously held by Kim's late predecessors, his grandfather Kim Il-sung and father Kim Jong-il.

Delegates at the congress adopted a resolution on "thoroughly implementing the tasks set forth" by Kim in a report delivered in the earlier sessions of the congress. The full text of the resolution was not released.

In the report, Kim defined the United States 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.

Following the closure of the congress, Kim paid tribute at the Kumsusan Palace of the Sun, where the bodies of his father Kim Jong-il and his grandfather and state founder Kim Il-sung lie in state.

The eight-day party congress was the longest after the fifth one was held for 12 days in 1970. The previous congress in May 2016 was held for four days.

North Korea said it will convene a Supreme People's Assembly meeting in Pyongyang on Sunday to discuss what was put forth during the party congress.

"The session will discuss the organizational issue and the issue of adopting a law on the five-year plan for national economic development and the issue of fulfillment of the state budget," KCNA said. (Yonhap)