Firefighters at the scene of an explosion at a Unipetrol plant in Kralupy nad Vltavou. Picture: Milan Kammermayer/Reuters Picture: Milan Kammermayer/Reuters

Prague - Six people were killed and two were injured in an explosion in a chemical factory in the Czech Republic, officials said on Thursday.

The explosion occurred inside a plant located in the town of Kralupy nad Vltavou, north of the capital Prague. Unipetrol, a Czech oil processor and plastics producer, said the blast took place inside one of the storage tank for fuels and additives in its refinery.

It was not immediately clear what caused the blast.

Regional firefighters confirmed that six people were killed and that two injured people were sent to hospitals. Spokesman Petr Svoboda said there was no danger of further explosions at the site.

Firefighters work at the scene of an explosion at a plant of Czech refinery and chemicals group Unipetrol in Kralupy nad Vltavou. Picture: Milan Kammermayer/Reuters

Petr Holecek, the town's mayor, told Czech public television a tank with an unspecified substance exploded. Speaking from the site of the explosion, Holecek also said he believed there was no danger to the town.

No dangerous substances have leaked out, according to police spokeswoman Marketa Jonova.

AP