Speaking in London, Foreign Minister Julie Bishop said while North Korea’s undertaking “was a step in the right direction”, the nation had in the past made promises but quickly broken them.

“In the past North Korea has made promises and failed to honour them, so we need to see verifiable steps that it will abandon nuclear tests and its nuclear program,” Ms Bishop said.

“Let’s hope they will take verifiable steps to prove they are genuine in banning their illegal nuclear weapons and testing,” she said.

North Korea announced on Saturday (AEST) that it had suspended nuclear and long-range missile tests, effective immediately, and scrapped its nuclear test site ahead of planned summits with South Korea and the United States.

North Korean leader Kim Jong-un said his country no longer needed to conduct nuclear tests or intercontinental ballistic missile tests because it had completed its goal of developing nuclear weapons, the Korean Central News Agency (KCNA) said on Saturday.

North Korea said that to create an “international environment favourable” for its economy, it would “facilitate close contact and active dialogue” with neighbouring countries and the international community.

It was the first time Kim directly addressed his position on North Korea’s nuclear weapons programs ahead of planned summits with South Korean President Moon Jae-in next week and with US President Donald Trump in late May or early June.

With growing pressure from Washington for complete denuclearisation of the Korean peninsula, US President Donald Trump welcomed the “progress”, saying he was looking forward to “our summit”.

“North Korea has agreed to suspend all Nuclear Tests and close up a major test site. This is very good news for North Korea and the World – big progress! Look forward to our Summit,” Mr Trump wrote on Twitter.

North Korea has agreed to suspend all Nuclear Tests and close up a major test site. This is very good news for North Korea and the World – big progress! Look forward to our Summit.

— Donald J. Trump (@realDonaldTrump) April 20, 2018

The North’s decisions were made in a meeting of the ruling party’s full Central Committee which had convened to discuss a “new stage” of policies.

David Wright, co-director of the Global Security Program at the Union of Concerned Scientists, said the move showed Kim was serious about denuclearisation talks.

“We’re all looking for evidence that Kim is really serious about negotiations, and announcements like this certainly suggest he is, and that he is trying to make clear to the world that he is,” he said.

The news comes as North and South Korea have opened up a direct hotline connecting the neighbours’ leaders ahead of next week’s closely watched summit.

The phone line, which the presidential office in Seoul said was tested on Friday, is to allow discussions between the offices of South Korea’s Mr Moon and Kim.

Next week’s meeting, only the third between the estranged neighbours, is expected to take place in the border village of Panmunjom.

Mr Moon is hoping to raise the issue of denuclearisation with Kim and discuss replacing the existing ceasefire arrangement between North and South Korea – the two countries are still technically at war – with a lasting peace arrangement.

He said agreements about denuclearisation, establishing a peace regime and normalisation of relations between the Koreas and the US should not be difficult to reach through the summit – and the summit planned between Kim and Mr Trump.

“I don’t think denuclearisation has different meanings for South and North Korea. The North is expressing a will for a complete denuclearisation,” Mr Moon said on Friday (Thursday local time) during a lunch with chief executives of Korean media companies.

“They have not attached any conditions that the US cannot accept, such as the withdrawal of American troops from South Korea. All they are talking about is the end of hostile policies against North Korea, followed by a guarantee of security,” he said.

CIA Director Mike Pompeo met Kim this month to discuss the proposed summit with Mr Trump and reported that the North Korean leader was not demanding the withdrawal of all US forces as a precondition for the meeting, a US official briefed on Mr Pompeo’s trip told Reuters.

Mr Trump said on Wednesday that Mr Pompeo formed a “good relationship” with Kim when he met him and the US President said he hoped the summit would be successful.

But Mr Trump warned he would call it off if he did not think it would produce results.

“If we don’t think it’s going to be successful, we won’t have it,” Mr Trump said. “If the meeting when I’m there isn’t fruitful, I will respectfully leave the meeting.”

In Geneva on Thursday, US Disarmament Ambassador Robert Wood told a news conference North Korea must show that it is “serious about getting rid of its nuclear weapons program” and take “concrete steps”, adding: “We’ve got a long way to go.”

-with agencies