Fire brigades from around the Campo de Gibraltar area have been brought in to fight a blaze that broke out at around 3pm at the Indorama petrochemical plant in San Roque on Tuesday.
The fire at the plant located in the Guadarranque industrial estate produced a huge column of thick black smoke visible from the entire bay of Algeciras and Gibraltar.
The Junta de Andalucia activiated its Plan de Emergencias Exterior on Tuesday evening, although it said that no one had been injured and that nearby homes had not been ordered to be evacuated.
The Cadiz province's Consortium of Fire Brigades said that initially units had been deployed from the stations in Algeciras, San Roque, La Línea de la Concepción and Gudacorte, in Los Barrios.
Reinforcements were then sent in from Cadiz, Jerez de la Frontera and Chiclana, with more than 70 firefighters at the scene.
The first emergency calls reported the sound of an explosion in a storage warehouse at the Indorama plant.
The factory produces of purified terephthalic acid (PTA) to be used in the production of polyester.
When the fire started the wind was from the south and it was hoped that Gibraltar would escape the thick black smoke, but that changed during the afternoon and it began to be blown towards the Rock. The Gibraltar government issued a warning to stay indoors and keep all windows and doors closed until an analysis had been carried out into the content of the smoke, and said it had offered assistance from the Gibraltar Fire & Rescue Service to the Spanish authorities.
The Gibraltar authorities continued to issue updates, and at 7pm said the smoke appeared to be moving west across the Bay and away from the Rock and was still being monitored, but there was no reason to believe it was toxic.
The blaze was reported to be close to being controlled at 6.20pm.