A teenage Pakistani tennis player, Zainab Ali Naqvi, died of a suspected heart attack after collapsing in her room following a practice session ahead of an ITF junior tournament in Islamabad. (More Sports Tennis)

The 17-year-old died while being taken to hospital late on Monday night. She was accompanied by her grandmother who sought help after the youngster fainted.

"It is very sad because Zainab was a very promising player on the women's circuit and enthusiastically working hard to win the ITF junior competitions," a senior Pakistan Tennis Federation official said.

A police official handling the case said doctors declared her dead after she was brought to an Islamabad hospital.

"The doctors suspect a heart attack and have termed it as a natural cause of death and her parents also didn't want any postmortem and they have been handed over her body for transportation back to Karachi," he said.

The PTF official said on condition of anonymity that doctors suspected hers to be a case of Hypertrophic Cardiomyopathy, a disease in which the heart muscle becomes thick.

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In its official statement on the incident, the PTF offered condolences to the young player's family, saying the incident has caused "profound grief"

"Mr. Aisam-ul-Haq Qureshi, the President of the Pakistan Tennis Federation, Senator Salim Saifullah Khan, Ex- President PTF, PTF Council Members, and the tennis fraternity at large offer their heartfelt condolences to the bereaved family," it said.

As a mark of respect to the deceased player, all the Tuesday matches of the ITF event were rescheduled for Wednesday.