Pyongyang, North Korea - Kim Jong-un said North Korea could "get along well" with the US if it acknowledged Pyongyang's nuclear status, but dashed hopes of a diplomatic thaw with Seoul.

Speculation is mounting that President Donald Trump may seek a meeting with Kim when he travels to China later this year, after attempts to hold a summit last year failed.

The newly re-elected leader made a direct appeal to the US as a landmark congress of North Korea's ruling Workers' Party drew to a close on Wednesday evening.

If Washington "respects our country's current (nuclear) status as stipulated in the Constitution... and withdraws its hostile policy... there is no reason why we cannot get along well with the Unites States," Kim said, according to the Korean Central News Agency.

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But Kim struck a far more combative tone when he addressed South Korea.

North Korea has "absolutely no business dealing with South Korea, its most hostile entity, and will permanently exclude South Korea from the category of compatriots", he said.

"As long as South Korea cannot escape the geopolitical conditions of having a border with us, the only way to live safely is to give up everything related to us and leave us alone."

A "grand" military parade marked the end of the Workers' Party congress, a MAJOR event that directs state efforts on everything from foreign policy to war planning.

Pyongyang said a range of military units took part in the event, including troops who fought in Ukraine and those stationed near the inter-Korean border.

Held just once every five years, the days-long congress offers a rare glimpse into the workings of a nation where even mundane details are shrouded in secrecy.

"Our military will immediately launch a fierce retaliatory attack against any military hostile act committed by any force that infringes upon the sovereignty... of our country," Kim said at the parade.