NEW DELHI — The women who died after sterilization surgery in the Indian state of Chhattisgarh might have been given antibiotic pills contaminated with rat poison, a senior official said on Friday.

Sonmoni Borah, the divisional commissioner in the district of Bilaspur, in Chhattisgarh, said that tablets of the antibiotic ciprofloxacin that were seized in police raids of Mahawar Pharma, a small company supplying medicines to the state government, were found to contain the chemical zinc phosphide.

“If you do a quick Google search, you will find it is rat poison, and the women were displaying symptoms similar to poisoning,” Mr. Borah said in a telephone interview. State officials issued an urgent warning on Friday to practitioners across the state, telling them to stop distributing or using ciprofloxacin “with immediate effect,” he said.

Mr. Borah said supplies of zinc phosphide were found at a pharmaceutical plant, Mahawar Pharma, and that the chemical “was mixed during manufacturing.”