A “danger alert” flashed at the plant of Haldia Petrochemicals Ltd (HPL) after Friday’s fire was lifted on Sunday amid hopes operations could resume in “three to four days”.

Ashok Ghosh, the plant head, said the fire that had left 15 staffers injured had been “completely extinguished and brought under control”. “We expect plant to restart within three to four days.” The alert was issued after the fire on Friday. On Sunday, a siren went off at 10am, signifying the alert had been removed.

The fire had been blamed on a gas leak in the naphtha cracker unit while repairs were on. Ghosh said a special valve, brought from Chennai, would be fitted into the damaged portion.

HPL produces polymer that goes into making plastic material. It processes naphtha, a crude oil derivative, to produce polymer and chemicals.

Citu leaders met the families of the injured staffers. Niranjan Sihi, the district secretary of Citu, demanded that the HPL management bear the cost of the families’ expenses on travelling to and staying in Calcutta where many of the injured employees are undergoing treatment in hospitals.

Company officials have said that all costs “associated with treatment” would be paid.

The Chatterjee Group is majority owner of HPL while Bengal government has a significant minority stake.

HPL is one of the largest producers of polymers in India and the biggest in the east. Several plastics goods makers, employing lakhs of people, depend on HPL for raw materials.