We do not desire the collapse of North Korea: S Korean Prez Moon Jae-in

He did not directly criticise Trump - who two days earlier threatened from the same podium to "totally destroy" North Korea

South Korean President Moon Jae-In said today he did not seek North Korea's collapse, using an address to the United Nations to urge a scaling down of sky-high tensions.

Moon, a longtime dove who was elected in May, warned North Korea to end its string of nuclear and missile tests but also promised help if the communist neighbour changed course.

"We do not desire the collapse of North Korea. We will not seek reunification by absorption or artificial means," Moon told the UN General Assembly.

"If North Korea makes a decision even now to stand on the right side of history, we are ready to assist North Korea together with the international community," he said, as stony- faced North Korean delegates listened in the front row.

Moon will later hold a three-way meeting with US President Donald Trump and Japanese Prime Minister Shinzo Abe, two right-leaning leaders who have pressed to punish North Korea.

Moon did not directly criticise Trump — who two days earlier threatened from the same podium to "totally destroy" North Korea — but appealed for calm.

"The situation surrounding the North Korean nuclear issue needs to be managed stably so that tensions will not become overly intensified or accidental military clashes will not destroy peace," Moon said.

He quoted late president Ronald Reagan, a hero for US conservatives, in saying: "'Peace is not absence of conflict; it is the ability to handle conflict by peaceful means.'" A US official said that Trump would later yesterday make an announcement of further sanctions on North Korea.

Moon voiced support for sanctions, calling for all nations to implement the latest UN Security Council resolution that ban North Korea's textile exports and end contracts for guest workers.