North Korea has suspended its sole remaining major project with the South after weeks of threats against the United States and South Korea.

North Korea's decision to all but close the Kaesong industrial park coincided with speculation that it will carry out some sort of provocative action.

The speculation has centred around another nuclear weapons test or missile launch.

Tension has been rising since the United Nations imposed new sanctions against the North in response to its third test of a nuclear weapon in February.

Pyongyang has been further angered by weeks of joint military exercises by South Korean and US forces and threatened both countries with nuclear attack.

Russian President Vladimir Putin said conflict on the peninsula could cause greater devastation than the Chernobyl nuclear disaster in 1986.

UN Secretary-General Ban Ki-moon said North Korea could not go on "confronting" the authority of the Security Council and challenging the international community.

"I sincerely hope that they will fully comply with the relevant Security Council resolutions.

This is an urgent and earnest appeal from the international community, including myself," Mr Ban said.

Earlier, South Korea's Defence Ministry has said that North Korea does not appear to be preparing for a fourth nuclear test in the near future.

This view is based on its reading of activity around the test site.

North Korean authorities told embassies in Pyongyang they could not guarantee their safety from Wednesday.

They said conflict was inevitable amid joint US-South Korean military exercises due to last until the end of the month.

No diplomats appear to have left the North Korean capital.

A South Korean government official, quoted by Yonhap news agency, said a North Korean general had told diplomats at the weekend that the situation remained "grave".

But he made no mention of Pyongyang's appeal to consider leaving by Wednesday.

US Secretary of State John Kerry visits Seoul later this week.

North Korea will hold celebrations and possibly military demonstrations next Monday to mark the birth date of its founder, Kim Il-Sung - grandfather of the current leader Kim Jong-un.

Pyongyang has moved what appeared to be a mid-range Musudan missile to its east coast, according to media reports last week.

Concern withdraws staff

Irish aid agency Concern has announced that it is withdrawing its staff from North Korea later this week.

Concern is one of only six international Non-Governmental Organisation working in North Korea.

Speaking on RTÉ’s Morning Ireland Paul O'Brien, Overseas Director with Concern, said the decision to withdraw was made after a warning was issued by the North Korean government.

The warning issued by the North Korean government was that it could no longer take responsibility for the safety of staff working with international aid agencies.