SEOUL (AFP, REUTERS) - South Korea on Saturday (April 21) welcomed the decision by the North's leader Kim Jong Un to cease its testing of nuclear weapons and ballistic missiles.

"North Korea's decision is meaningful progress for the denuclearisation of the Korean Peninsula, which the world wishes for," the presidential office in Seoul said in a statement.

"It will create a very positive environment for the success of the upcoming inter-Korean and North-US summits."

US President Donald Trump has welcomed a statement by North Korean leader Kim Jong Un that he will suspend nuclear and missile tests immediately and abolish a nuclear test site, and Trump said he looked forward to a summit with Kim.

"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," Trump said in message on Twitter.

Japan, however, is not satisfied with North Korea's pledge to halt nuclear tests and intercontinental missile launches, its defence minister said on Saturday, warning that Tokyo will continue to put maximum pressure on Pyongyang.

"We can't be satisfied," Mr Itsunori Onodera told reporters in Washington, saying North Korea did not mention "abandonment of short-range and medium-range ballistic missiles".

Ordinary South Koreans were also cautious after the latest announcement. "I don't think we can completely trust anything North Korea says because North Korea isn't a normal country," said Kim Han Nuri, 23, out in Seoul on a sunny spring morning.

North Korea's leader Kim Jong Un announced Pyongyang will carry out no more nuclear or intercontinental ballistic missile tests and will shut down its atomic test site, the North's state media reported on Saturday.

The declaration, long sought by the US, will be seen as a crucial step in the fast diplomatic dance on and around the Korean peninsula.

It comes less than a week before Kim meets South Korean leader Moon Jae In for a summit in the Demilitarised Zone that divides the peninsula, and ahead of a much-anticipated encounter with US President Donald Trump.

"As the weaponisation of nuclear weapons has been verified, it is not necessary for us to conduct any more nuclear tests or test launches of mid- and long range missiles or ICBMs," Kim told a ruling party meeting.

"The northern nuclear test site has completed its mission," he added at the gathering of the central committee of the Workers' Party, according to the official KCNA news agency.