North Korea: Seoul says fourth nuclear test is not imminent

South Korea has retracted claims that North Korea is preparing to conduct a fourth nuclear test, hours after the unification minister in Seoul said there were signs of increased activity at the North's main testing site.

But as officials in Seoul dampened speculation over a nuclear test, North Korea said it would withdraw its workers from the Kaesong industrial zone, a venture with the South located north of the heavily armed border separating the countries.

The South's defence ministry said the reported movements around the Punggye-ri site were routine and did not signal an imminent test. "We found there had been no unusual movements that indicated it wanted to carry out a nuclear test," a defence ministry spokesman said.

Earlier on Monday, the South Korean unification minister, Ryoo Kihl-jae, was reported as having told a meeting of MPs that Seoul had acquired evidence of increased movement of vehicles and personnel at Punggye-ri.