LJUBLJANA, May 12 (Xinhua) -- Six people died in an explosion in a chemical factory in southern Slovenia, national TV channel TV Slovenia reported on Thursday.

       It said the accident, which occurred in Kocevje, about 63 km southeast of the capital Ljubljana, is the biggest industrial accident in the country since Slovenia's independence in 1991.

       The accident was likely caused by a human error as two chemicals were mixed together causing the explosion followed by a large fire, local media reported.

       Another twenty people needed medical help with one severely injured being treated in a hospital in Ljubljana.

       Some buildings in the vicinity of the factory have also been damaged while citizens of Kocevje were advised to remain indoors for several hours.

       The factory, Melamin, which has over 200 employees, produces chemical products that are used in construction, textile, painting, paper, tire, furniture and shoe industries.

       Vladimir Prebilic, mayor of Kocevje, told reporters the explosion has not caused environmental damage.