At least 14 babies have died at a hospital nursery in Pakistan.

The fire started at around 7am on Wednesday on the third floor of a major government hospital - the Pakistan Institute of Medical Sciences.

Some reports suggested one child was rescued.

Pakistan's prime minister Shehbaz Sharif has ordered an investigation into the fire. Local reports say it started after the compressor of an air-conditioning unit exploded inside the nursery.

Pakistan's prime minister Shehbaz Sharif said: "A tragedy involving children is an irreparable loss."

His office said that "those responsible should be identified, ⁠and the strictest action should be ​taken".

Pakistan's President Asif Ali Zardari extended his "heartfelt condolences and sympathy to the bereaved families".

"The responsible parties in the incident should be identified and action taken in accordance with the law," he said in a post on X.

"Effective fire safety and emergency arrangements should be ensured for the protection of patients in hospitals, especially newborn babies."

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Firefighters stopped the fire, with rescue teams carrying out cooling operations at the site, local media reported.

The families of some of the victims gathered outside the hospital, many in tears.

The incident is among the deadliest hospital ​fires in recent years in Pakistan.

Government healthcare ⁠is subsidised in Pakistan, but facilities are under-resourced and overburdened, while watchdogs have frequently criticised ‌state-run facilities as mismanaged.

Pakistan has suffered several serious fires in recent years, including at a shopping centre in the country's largest city of Karachi that killed 67 people in January.

At least 16 people were killed in a chemical factory fire in August 2021, also in Karachi.