North Korea will suspend nuclear and missile tests effective immediately and abolish a nuclear test site in a bid to pursue economic growth and peace on the Korean Peninsula, state media said, 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 (ICBM) tests because it has completed its goal of developing nuclear weapons, the country's official Korean Central News Agency (KCNA) said.

"To guarantee suspension of nuclear tests in a transparent manner, the republic's northern nuclear test site will be abolished," the KCNA said, after Mr Kim convened this year's first plenary session of the Central Committee of the ruling Worker's Party.

The KCNA said the country was making the move to shift its national focus and improve its economy.

"The overall projects of the party and the country will be geared towards building of a socialist economy, and all our efforts will be made towards it."

North Korea also said it will engage in talks with the international community, paving the way for the summit with South Korean President Moon Jae-in, planned for next week, and a meeting with US President Donald Trump in late May or early June.

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Some analysts believe Mr Kim is entering the negotiations from a position of strength and is unlikely to accept a significant cut of his arsenal.

South Korean and US officials have said Mr Kim is likely trying to save his broken economy from heavy sanctions.

Mr Trump welcomed the statement about the meeting and said he looked forward to a summit with Mr Kim.

"North Korea has agreed to suspend all nuclear tests and close up a major test site," he said on Twitter.

"This is very good news for North Korea and the world — big progress!

"Look forward to our summit."

Mr Trump added that he received a message from Mr Kim stating: "North Korea will stop nuclear tests and launches of intercontinental ballistic missiles … [and will] shut down a nuclear site in the country's Northern Side to prove the vow to suspend nuclear tests."

China's Ministry of Foreign Affairs said it welcomed North Korea's move, which it said would help ease tensions on the Korean peninsula and promote denuclearisation.

"The Chinese side believes that North Korea's decision will help ameliorate the situation on the peninsula," it said in a statement.

"China welcomes this."

The European Union's Foreign Affairs Chief said Saturday (local time) that North Korea's announcement to stop nuclear tests was a positive step and called for an "irreversible denuclearisation" of the Asian country.

North discusses 'new stage' of policies

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.

The Korean Workers' Party's Central Committee declared it a "great victory" in the country's official "byungjin" policy line of simultaneously pursuing economic and nuclear development.

The committee unanimously adopted a resolution that called for concentrating national efforts to achieve a strong socialist economy and "ground-breaking improvements in people's lives".

"To secure transparency on the suspension of nuclear tests, we will close the republic's northern nuclear test site," the party's resolution said.

The agency quoted Mr Kim as saying during the meeting: "Nuclear development has proceeded scientifically and in due order and the development of the delivery strike means also proceeded scientifically and verified the completion of nuclear weapons."

"We no longer need any nuclear test or test launches of intermediate and intercontinental range ballistic missiles and because of this the northern nuclear test site has finished its mission."

Seoul says Mr Kim has expressed genuine interest in dealing away his nuclear weapons. But North Korea for decades has been pushing a concept of "denuclearisation" that bears no resemblance to the American definition, vowing to pursue nuclear development unless Washington removes its troops from the peninsula.

Tensions eased significantly after, in a New Year's speech, Mr Kim called for lower military tensions and improved ties with South Korea.

It sent a delegation to the Winter Olympics held in South Korea and agreed to meet with Mr Moon and Mr Trump to discuss denuclearisation of the Korean Peninsula.

The ruling party's plenary meeting on Friday was convened to discuss "policy issues of a new stage" to meet the demands of the current "important historic period," the KCNA said.

A North Korean missile is launched during a test in May last year. ( Supplied )

AP/Reuters