A number of North Korean workers at an inter-Korean industrial complex have recently suffered fever and headaches due to possible exposure to toxic chemicals, informed sources said Wednesday.



The suspected benzene poisoning has prompted two car parts makers at the Kaesong Industrial Complex to suspend the operation of related production lines, according to the sources.



North Korea has claimed that its workers were apparently poisoned by benzene as many of them were involved in a leather-heating process to manufacture handle covers and other goods.



Citing its initial probe, however, the South Korean government said the chemical has not been used at the workplace. The exact number of workers affected remains unconfirmed.



"The results of a preliminary probe by the management committee for the Kaesong Industrial Complex showed that materials containing benzene are not used (there)," Lim Byeong-cheol, a spokesman for Seoul's unification ministry told reporters.



Seoul is conducting further investigation into the exact cause of the symptoms among the North's workers, Park said.



The Kaesong factory park, located just north of the inter-Korean border, is the last-remaining major joint venture between the two Koreas.



More than 100 South Korean small and mid-size companies employ around 50,000 North Korean workers at the complex.



