United Nations chief Antonio Guterres Thursday warned the world against "sleepwalking into war" over North Korea, as he called for diplomatic efforts to banish nuclear weapons from the Korean peninsula.

Speaking on a visit to Japan, Secretary-General Guterres said: "The worst possible thing that could happen would be for us all to sleepwalk into a war that might have very dramatic circumstances."

The UN Security Council has imposed three rounds of sanctions over the past year against North Korea over its increasingly powerful missile and nuclear tests.

Guterres said those sanctions need to be implemented "by North Korea first of all, but also fully implemented by all the other countries whose role is crucial".

He urged "diplomatic engagement that allows for...denuclearisation (of the Korean peninsula) to take place in a peaceful way".

"It is important for all parties to understand the urgency of finding a solution," he told reporters at a later briefing.

Speaking alongside Guterres, Japanese Prime Minister Shinzo Abe echoed the call to "fully implement United Nations Security Council resolutions" and hold "meaningful dialogue toward denuclearisation".

The secretary-general's trip comes after Jeffrey Feltman, the UN's political affairs chief, visited North Korea earlier this month.

Feltman said he had been told in Pyongyang that North Korea wants to avoid war and said he "fervently" hoped the "door to a negotiated solution will now be opened wide".

On Tuesday, US Secretary of State Rex Tillerson said Washington was ready to talk to Pyongyang "without preconditions", interpreted by many as a shift in the US position.

Washington's top diplomat told the Atlantic Council policy forum that North Korea is welcome to talk about anything at a first meeting -- even the weather.

However, the White House and Tillerson's own department later stressed that the US position on North Korea "had not changed".

"The secretary was not creating a new policy, our policy remains exactly the same as it was," State Department spokeswoman Heather Nauert said Wednesday.

Asked about Tillerson's comments, Guterres said he would "not like to comment on expressions that sometimes might not translate exactly the thinking" of the administration.

"Dialogue must have an objective and the objective for us is to achieve the denuclearisation of the Korean peninsula and to do it in a peaceful manner," stressed the UN chief.

Asked if he would be willing to meet North Korean leader Kim Jong Un, he said: "Meetings only make sense if there is a purpose to those meetings. I am ready to go anywhere at any time when it is useful but I'm not aiming...just to be in the cameras of the television."

"We are available, but we can only mediate when both parties accept our mediation."

Source: AFP