An independent investigation into the deaths of more than a dozen women who had undergone sterilisation surgery in India, has reportedly said that that doctor who carried out the procedures used the same needles every time.

The AFP news agency reported that a probe by four public health organisations concluded that the women had been subject to unhygienic conditions and that some probably died of infection.

The women were treated in two state-run sterilisation health camps in a village called Pandari, in the state of Chhattisgarh. Free sterilisation surgery is being offered in India as part of a government programme to curb the country’s population growth. As it stands, India is expected to overtake China as the most populous nation by 2050.

Doctor RK Gupta, who carried out the laparoscopic tubectomy operations, was arrested on 12 November. He denied reports that his equipment was rusty or dirty and said it was the government's duty to control the number of people that turned up to the clinic.

However the investigation reportedly said that the same injection needle and syringe and suture needle were used to treat all the women and that these were not sterilised. Additionally, staff did not change their gloves between each patient.

Dr Gupta faces charges of causing death by negligence, which he denies, saying he is being made a “scapegoat”. He believes post-op medication may have been contaminated and that this could have caused the deaths.

The government of Chhattisgarh banned five batches of drugs and a batch of surgical cotton wool pending further investigations – but the independent investigation found that although tainted drugs could have caused the deaths, at least seven of the women appeared to have died of septicaemia.

The Indian government is also said to have ordered an investigation.