North Korea has ignored a plea by South Korean businessmen to visit a joint industrial zone on Tuesday for talks on its future, an official in Seoul said, amid fears of a permanent closure.

About 10 leaders of the group of South Korean firms with factories at the Kaesong complex sought to visit the site -- the last remaining point of contact between the two Koreas.

But the North has not responded to the request, making the trip impossible for Tuesday, an official at Seoul's unification ministry handling cross-border affairs told AFP.

The complex -- built 10 kilometres (six miles) north of the tense border in 2004 as a rare symbol of inter-Korean cooperation -- has fallen victim to a recent surge in military tensions.

Pyongyang banned entry by southerners and pulled out all its 53,000 workers from the complex in early April.

Seoul last week ordered all remaining South Koreans to leave after Pyongyang rejected its call for talks.

Forty-three South Koreans returned early Tuesday but seven remained to settle unresolved administrative issues over unpaid taxes and wages for North Korean workers.

It is unclear when the seven will be able to return home, the ministry official said.

South Korean companies with interests at Kaesong have expressed shock at the sudden pullout, which has taken a heavy toll on their businesses. Seoul has promised to draw up measures to support the companies.

Previously the complex -- where North Koreans worked at factories for 123 South Korean firms -- remained largely immune to strains in cross-border relations.

Tension has been high since the North, angered by fresh UN sanctions sparked by its nuclear test in February and South-US military drills, issued a series apocalyptic threats of a nuclear war against Seoul and Washington.

The North since last week has threatened "final decisive" action on Kaesong if the situation worsens.

The pullout of South Koreans is "a cunning and mean-spirited trick aimed at passing blame to the North for the plight of the complex", the North's ruling communist party newspaper said Monday.