A Canadian businesswoman who was staying at the home of a Pakistani cabinet minister has died in mysterious circumstances, raising suspicions of foul play.

Kafila Siddiqui, a former Toronto-area resident, had been staying in the capital city of Islamabad at the home of the Minister of State for Communications Muhammad Shahid Jamil Qureshi, The Globe and Mail reported.

Siddiqui, a 40-year-old mother of a five-year-old boy, was in critical condition when the minister brought her to hospital on Saturday, but she was declared dead on arrival, The Globe reported.

Local Pakistani media reports quoted Qureshi as saying he found Siddiqui either unconscious or vomiting on the floor in her room.

An English-language Pakistani paper, the Daily Times, quoted a physician as saying Siddiqui's apparent cause of death was heart failure, but that scars were found on her face and neck.

A relative of Siddiqui, who had moved to Islamabad to run an investment consulting firm, told The Globe that her husband had been unable to talk to her for several weeks and that he feared she was being held against her will at the minister's house.

Siddiqui's husband Suleman Qaiser filed a missing person's report with police, a brother-in-law said in an interview from Richmond Hill, just north of Toronto. He said Qaiser had told him: "I'm very worried. She's not telephoning me. I tried to contact her but there were no replies."

"I was thinking she was ill or something like that. I thought she had been admitted to hospital for some disease and after that she died," the brother-in-law told The Globe on Sunday.

"But their story was quite different."

International News quoted her brothers as saying she and the minister were in a joint venture "to get aid from the Canadian government."

Siddiqui's husband was in Karachi on Sunday organizing her burial, the brother-in-law said. He said Siddiqui's husband had initially remained in Canada while his wife was in Pakistan because he was on probation at a new job.

The brother-in-law said when Siddiqui's husband tried reaching his wife by phone recently, the minister said 'She's not here. I don't know about her.' "

Foreign Affairs in Ottawa confirmed they were aware that a Canadian citizen had died in Pakistan and said consular officers have contacted the family to provide assistance. A spokesperson would not provide further details.