ISLAMABAD: National Accountability Bureau (NAB) on Monday said it had suspended a probe into a graft scandal involving the prime minister until an inquiry into the death of an officer investigating the case concludes.

Kamran Faisal was found dead on Friday in the government hostel where he lived in Islamabad with colleagues from the anti-corruption watchdog.

According to initial findings of an autopsy, he committed suicide. He was reportedly found hanging from a ceiling fan, but Faisal's family say he had marks on his wrists and dispute that he killed himself.

“The proceedings in RPPs (Rental Power Plants) case would remain pending till the conclusion of the inquiry in Kamran case,” said a statement by the watchdog attributed to its chairman Fasih Bokhari.

The long-running probe involving Prime Minister Raja Pervez Ashraf and other officials relates to allegations of kickbacks during Ashraf's tenure as minister for water and power.

NAB added that it will conduct its own inquiry into Faisal's death if other investigations fail to satisfy them.

The government had earlier appointed a retired judge to probe the death. The former Supreme Court judge, Justice (retd) Javed Iqbal will submit a report in two weeks, Interior Minister Rehman Malik told reporters late Sunday.

The watchdog said Faisal was a junior investigations officer working on the case against Ashraf, whose arrest was ordered by the Supreme Court last week in a move that sparked panicked rumours of a “soft coup” against the government.

The court has since adjourned the case to January 23 and a further perceived threat to the government, a rally of tens of thousands led by a cleric outside parliament, has dispersed.

The prime minister on Monday withdrew a petition asking the Supreme Court to review its orders from March 30, 2010 for action against all officials involved in the alleged scam, including himself.

According to NAB, Faisal suffered from “mental stress” and “psychological issues”. He had asked to be taken off the case, but the Supreme Court refused a written request on January 7 and ordered he be reinstated.

Suicide is frowned upon under Islam and Faisal's father, Abdul Hameed, told AFP on Monday that he believed his son was murdered.

“I have seen marks on his wrist. His hands were apparently tied before his death. He is a martyr,” he said by telephone from his home in Punjab province.

The retired civil servant said he wanted justice for his son but was doubtful that a judicial commission would get to the bottom of his death.

“I want a fair investigation so that culprits be exposed,” he said.

Employees in the eastern city of Lahore on Monday observed a “pen down” strike -- turning up to work but refusing to work -- demanding an independent and transparent investigation, and compensation for the family, said NAB official Atiqur Rehman.

Doctor Shaukat Kiyani at the Services General Hospital in Islamabad where the autopsy was performed, said the initial conclusion was suicide but that a final verdict was expected in a week or 10 days' time.