North Korea warned rival South Korea it risks triggering a "destructive" showdown and accused the United States of abusing its power on the UN Security Council, in a fiery address Tuesday.

Hours after South Korea paraded a missile capable of pinpoint strikes across the border, North Korea's Vice Foreign Minister Pak Kil-Yon said his government's "generous" efforts to improve relations had hit a "confrontational approach" from the South.

Pak told the UN General Assembly meeting of world leaders and senior ministers that the South's attitude is "creating the danger of driving relations back into a destructive stage again."

Amid signs that North Korea is expanding production of weapons grade fissile material, South Korea's President Park Geun-Hye said earlier in Seoul that the North's nuclear bombs pose a "grave threat".

To reinforce the state of alert, South Korea showed off a new missile capable of high-precision strikes at a parade in the capital which was attended by US Defense Secretary Chuck Hagel.

The North Korean minister said "US hostile policy" was the cause of tensions on the Korean peninsula and accused the United States of forcing through UN sanctions over a ballistic rocket launch.

The UN Security Council extended sanctions against the North in January for launching a rocket considered equivalent to a long range missile and after the North's third nuclear arms test in February.

"It represents a typical example of how and for what purpose the power of the UN Security Council is being abused," Pak said, accusing the United States, one of five permanent members of the council, of "manipulation".

"The instances of the UN Security Council being abused by a certain state as a tool of its strategic interests should never go unchallenged," Pak said.

The sanctions followed weeks of talks between the United States and China, the North's key ally.

China has expressed growing concern about the North's nuclear program while seeking to revive six-country talks on the issue.

The North Korean minister said the 193-member UN General Assembly should have the final say on resolutions passed by the 15-member Security Council, the UN's supreme body on international peace and security matters.

"A specific state's high-handedness and arbitrariness undermining peace and security should be rejected in international relations with a view to achieve genuine cooperation and development among countries," Pak told the UN meeting.

The minister also condemned what he dubbed the "double standards" of UN human rights investigators who have criticized the North's record, the "unjust intervention, pressure and use of force" in Syria and the US embargo against Cuba.