A woman died after a former security guard at Lahore's Mayo Hospital posed as a doctor and performed surgery on her, police said on Monday.

Shameema Begum, aged 80, died on Sunday, two weeks after Muhammad Waheed Butt attempted to treat her back wound at the public hospital.

“We can't keep up with what every doctor and what everyone is doing at all times. It's a large hospital,” explained an administrative official from the hospital, who did not want to be named.

He said it was unclear what type of surgery the imposter had performed in the operating theatre, where a qualified technician was also present.

Pakistan's public hospitals, where patients are required to pay some money towards treatment, can often be inefficient and chaotic.

Begum's family paid Butt for the operation, and two further home visits to dress her wound.

But when the bleeding and pain worsened, her family returned her to the hospital, where they discovered what had happened.

Her body is being kept for an autopsy to ascertain whether her death was a result of complications from the botched surgery.

“The guard has been charged and is in police custody,” Lahore police spokesman Ali Safdar told AFP.

“Butt had posed as a doctor and made home visits to other patients in the past also.”

Mayo Hospital staff said Butt was fired two years ago for trying to extort money from patients.

Earlier in May, a man was arrested for posing as a doctor at Lahore General Hospital and extorting money from patients in the surgical ward.

In 2016, it was revealed that a woman posing to be a neurosurgeon conducted operations for eight months alongside qualified doctors at Lahore's Services Hospital, the second-largest health facility in Pakistan.