That meant South Korean managers and truckers taking raw materials from the South were still not able to reach the industrial zone.

Lines cut

Kaesong industrial park


  The park opened in June 2003 located near the North Korean city of Kaesong, about 70km northwest of Seoul

About 100 South Korean firms have set up factories in the park, mostly to assemble products using cheap North Korean labour

About 38,000 North Koreans work in the park producing or assembling items such as textiles, watches and cosmetic cases

Minimum monthly wage of $70 is paid to the North Korean state and not directly to workers

South Koreans travelling to the Kaesong zone need approval from North Korean officials before they can cross the border.

On March 9 North Korea switched off military phone and fax lines that were used to authorise border crossings.

It allowed crossings to resume a day later but kept the phone lines cut, meaning the two sides had to hand-deliver letters to authorise border crossings.

Then on Friday North Korea announced that all crossings were again suspended, without giving an explanation.

The jointly-run Kaesong industrial zone employs some 38,000 North Korean workers in about 100 South Korean-owned factories producing such goods as watches, clothes, shoes and kitchenware.

The zone relies on raw materials trucked in from the South, with the finished products then shipped back across the border.

'Paralysis'

On Sunday South Korean companies working in Kaesong urged the North to normalise border traffic, saying the border closure had led to a "complete paralysis of business operations" in the complex.

The move comes amid escalating tensions on the Korean peninsula, with North Korea preparing for what it says is the launch of an experimental communications satellite.

North Korea's neighbours, however, believe the launch, scheduled for early April, is cover for a test of a long-range missile.

Tensions between North and South Korea had eased significantly in the years following a landmark summit between the leaders of the two countries in June 2000.

But the past year has seen a rapid decline in relations following the election of Lee Myung-bak, as South Korean president.

Pyongyang has criticised as "confrontational" the policies of Lee, a conservative who has angered the North by ending the flow of unconditional aid to the impoverished country.