"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 statement from President Moon Jae-in's office said.

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An important step

By Laura Bicker, BBC News, Seoul

The declaration came in six dramatic bullet points on North Korea's state run news agency, and it is a significant statement.

Mr Kim says it is not necessary to conduct any more missile tests because nuclear weaponisation has been achieved. This echoes his previous statement during a New Year address that the state is satisfied it is a nuclear power.

After six nuclear tests North Korea may feel it does not need to upgrade its existing designs.

This is not denuclearisation as demanded by the international community. Although North Korea has said it will abolish its atomic test site, it is not promising to get rid of its weapons.