LJUBLJANA (AFP) - A worker hurt in an explosion at a chemical factory in Slovenia has died from his injuries, bringing the total number of people killed in the accident to six, local media reported on Friday (May 13).

The blast occurred on Thursday when a cistern exploded at a resin factory belonging to chemicals company Melamin in the municipality of Kocevje, some 60 kilometres south of Ljubljana.

"Unfortunately, our fears have been confirmed," Melamin general manager Srecko Stefanic told reporters.

The strength of the explosion "did not leave them any chance of survival", he said.

Initially, five people were reported to have been killed and six others injured, including two who were hospitalised with serious burns.

One of the two has since died in hospital and the other is still in critical condition, public radio reported. AFP was not able to confirm the information.

The tragedy was "caused by a human error", Mr Stefanic said, declining to give more information until the investigation has been completed.

Local authorities initially asked residents staying within a radius of 500 metres around the plant not to leave their homes and to close their windows as a precaution in case of toxic fumes.

The precautionary measure was lifted later on Thursday after officials confirmed there had been no negative impact on the environment.

Photos showed columns of black smoke billowing from the factory, which supplies resins for the paper, construction, wood, rubber and lacquer industry.

Nearly 200 people work at the factory of the company, founded in 1954, according to its website.