An explosion at a pharmaceutical factory in southern India on Wednesday, which killed at least 17 people and injured 36, was due to a chemical solvent leak, according to an internal government report accessed by Reuters on Thursday.

The blast came around noon at the privately-held Escientia Advanced Sciences in Andhra Pradesh, where nearly 400 employees make intermediate chemicals and active ingredients for export to the United States and other Western countries.

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Workers had been trying to plug a chemical leak when an explosion ripped through the unit, Srinivasa Rao Korada, chief financial officer of the Escientia Group, said on Thursday.

"Workers had noticed that leak, they were attending to it, and had almost plugged the leak when this happened," he said, adding it was not clear what triggered the leak.

Local police filed an initial formal report against the company following a complaint from a local government official saying a lack of precautionary measures could have led to the blast.

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The company is collaborating with authorities to investigate the reason for the leak, Korada said, adding that smoke and fire had prevented it from investigating immediately.

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