ISLAMABAD: A senior Pakistani investigator probing graft charges involving Premier Raja Pervez Ashraf was found dead in mysterious circumstances at his official accommodation here on Friday, police said, amid reports that he was "under pressure" due to the high-profile case.

Kamran Faisal , an assistant director of the National Accountability Bureau (NAB), was found hanging from a fan in his room at the Federal Lodges in Islamabad, police officials said.

Preliminary investigations suggested he had committed suicide, the officials said.

Islamabad Police chief Bin Yamin told reporters the cause of death would be established by an autopsy.

Faisal, whose body was sent to the state-run Pakistan Institute of Medical Sciences for autopsy, was one of two investigation officers probing allegations of graft in rental power projects.

The Supreme Court had last year directed NAB to take action against Prime Minister Ashraf and over 20 other suspects in connection with these allegations.

The allegations against Ashraf date back to his tenure as power minister.

On Wednesday, the apex court directed NAB to arrest Ashraf and other suspects.

NAB chief Fasih Bokhari told the court on Thursday that he lacked evidence to make the arrests.

Bokhari said investigators had not uncovered enough evidence against any of the suspects.

Bokhari visited the Federal Lodges after learning of Faisal's death.

He described the incident as "unfortunate." Geo News channel quoted its sources in NAB as saying that Faisal had been "under pressure" in connection with the probe into the power projects.

The sources further said Faisal had asked his superiors to remove him from the case.