MOL chairman-CEO Zsolt Hernádi and Energy Minister István Kapitány are en route, Magyar said.

In a post on Facebook, local news source Tiszaújvárosi Krónika said available information pointed to the explosion of a pyrolysis gasoline line at the MOL petrochemicals plant. Disaster protection officials have said local residents are not at risk, it added.

Dávid Dojcsák, the spokesman for the local disaster protection authority, told state news wire MTI that the fire at the plant was being extinguished and a mobile laboratory had been sent.

MOL told MTI that the explosion took place during a restart of the Olefin-1 plant. Firefighters have localised the fire, it added.

The oil and gas company confirmed that one person had died in the explosion and a several were seriously injured. Experts are investigating the circumstances of the accident, it added.