South Korean workers barred from factories in the North

Hundreds of workers from South Korea were today denied access to factories in the North as tensions between the two countries escalated.

North Korean leaders threatened to close the joint-venture Kaesong industrial zone last week but only acted on the threat this morning when border guards prevented 480 southern workers going to their jobs.

The blockade comes amid increasing hostility from Pyongyang which has threatened nuclear strikes on Seoul and Washington and declared the armistice ending the Korean War void.

The park at Kaesong, which opened in 2004 and last year produced $470 million worth of goods, is one of the few remaining symbols of co-operation between the North and South.

It employs 53,000 North Koreans and provides crucial hard currency. The complex is also a base for around 120 southern firms. Seoul’s Unification Ministry spokesman Kim Hyung-suk confirmed that 480 southerners planning to travel north today had been prevented.

The ministry urged Pyongyang to “immediately normalise” cross-border traffic in and out of Kaesong. The closure comes after North Korea said yesterday it would reactivate its main Nyongbyon nuclear complex, including a plutonium reactor and uranium enrichment plant capable of producing weapons-grade material.

The US has called on Russia and China to use their influence to persuade the North to change its course, which Secretary of State John Kerry called “dangerous” and “reckless”. Mr Kerry said: “The United States will defend and protect ourselves and our treaty ally, the Republic of Korea.” Two US warships have been sent to the region.