The decision came after a meeting of the ruling Worker's Party of Korea.
ADVERTISEMENTNorth Korea will suspend nuclear and missile tests immediately and abolish a nuclear test site in the northern part of the country in a bid to pursue economic growth and peace on the Korean peninsula.
The decision comes amid decreasing tensions on the Korean Peninsula ahead of a summit between the North and the South next week.
North Korea leader Kim Jong Un said in a statement his country no longer needs to conduct nuclear tests or intercontinental ballistic missile tests because it has completed weaponizing nuclear arms, said the Korean Central News Agency.
Kim said that to create an "international environment favorable" for its economy, it would facilitate close contact and active dialogue" with neighboring countries and the international community.
It marked the first time North Korea directly addressed its nuclear weapons programmes, ahead of the planned summit with South Korean President Moon Jae-in next week and a meeting with U.S. President Donald Trump in late May or early June.
Mr Trump has welcomed the news and said he looked forward to a summit with Kim:
The northern nuclear test ground of the DPRK (Democratic People's Republic of Korea) will be dismantled to transparently guarantee the discontinuance of the nuclear test," Korean Central News Agency (KCNA) said after Kim convened this year's first plenary session of the Central Committee of the ruling Worker's Party on Friday.
Japanese Defence Minister Itsunori Onodera said it was not the time to ease pressure on North Korea.
Japan has advocated a policy of maximum pressure to get the reclusive state to abandon its weapons programme.
Japanese Prime Minister Shinzo Abe who came back from his visit to Washington for talks with U.S. President Donald Trump also cautiously welcomed the move as a "forward motion" but said it must lead to verifiable denuclearisation.
South Korea's presidential office said the decision is a "meaningful progress" for denuclearization of the Korean peninsula.
"It will also contribute to creating a very positive environment for the success of the upcoming South-North summit and North-United States summit," a spokesman for the president's office, Yoon Young-chan, said in a statement.
North Korea has defended its nuclear and missile programmes as necessary deterrents against perceived U.S. hostility.
It has conducted numerous missile tests, and last year it detonated its most powerful nuclear bomb.
The tests and escalating rhetoric between Trump and Kim raised fears of war until, in a New Year's speech, the North Korean leader called for reduced military tensions and improved ties with South Korea and sent a delegation to the Winter Olympics in the South in February.