A local government spokesman said a preliminary investigation indicated the force of the blast killed an individual in a nearby neighbourhood.

The interior minister of Spain's Catalonia region, Miquel Buch, tweeted that the explosion on Tuesday caused one death and left six people injured while one person remained missing.

The civil protection agency in the Catalonia region called the blast a "chemical accident" and warned people in parts of the city of 800,000 and in nearby towns to refrain from going outside as a precaution.

Emergency services said that two of the injured were being treated for major burns.

Buch said the smoke from the resulting fire was not toxic but he also advised residents to remain inside.

Local residents posted videos showing the aftermath of the blast, with flames and a big column of black smoke emerging from an area dotted with big industrial tanks.

Fire departments sent 24 brigades to the area, the regional emergency service said.

Some local residents told Tarragona Radio that the blast could be heard from several kilometres away.

Tarragona is located 115 kilometres southwest of Barcelona, the regional capital of Spain's Catalonia region.

Since 2015, the city has housed a 1200-hectare "chemical hub," ChemMed, that was described as the largest of its kind in southern Europe.

The explosion comes just over a month after a blaze at a solvent and industrial residues recycling plant in the northeastern town of Montornes del Valles.

Australian Associated Press