An enormous explosion at a petrochemical plant in northeastern Spain has killed one person and injured at least eight others, according to authorities.

The regional fire service said on Twitter one person had died in a building affected by Tuesday's blast in the port city of Tarragona, where the plant of the Industrias Quimicas del Oxido de Etileno company is located.

The building in which the person died collapsed near the factory due to a shockwave from the explosion, local media reported.

The interior minister of Spain's Catalonia region said eight workers at the factory were injured, three seriously, and one person remained missing.

Spanish Prime Minister Pedro Sanchez's office said he was in touch with Catalan authorities, adding that the government was ready to "provide the necessary support due to this serious event, which has caused several injuries and substantial material damage".

The cause of the blast was not immediately clear [Reuters]

More than 20 fire trucks, 11 emergency medical service vehicles and a helicopter attended the incident. Video footage showed high flames and columns of smoke around the complex.

The civil defence agency advised people nearby to stay inside with doors and windows shut as a precaution, but added: "There is no evidence of a toxic cloud."

Local trains between Tarragona and neighbouring Port Aventura were suspended on police orders before later resuming services, the train operator Rodalies said, while the regional transport authority said some roads had been closed.