ISLAMABAD, Pakistan  —  The founder of Pakistan's nuclear weapons program has been barred from leaving Islamabad and has been questioned repeatedly amid an investigation into possible proliferation by the country's nuclear scientists, an acquaintance said Saturday.

The report about the restriction imposed on Abdul Qadeer Khan (search) came as officials said investigators were checking the bank accounts of eight scientists and administrators detained so far in the probe.

Khan has been questioned "many times" in recent weeks and is confined to Islamabad, said Zahid Malik (search), author of the book "Islamic Bomb" on Pakistan's nuclear program, who said he met Khan on Thursday.

"He's cooperating (with the investigation) but he's satisfied that he's done nothing wrong," Malik told The Associated Press.

A government official said on condition of anonymity that "security restrictions may have been increased" on Khan, but added that the scientist had "chosen to stay in Islamabad" while "debriefings" of laboratory employees take place.

Khan is lauded by his countrymen as the father of Pakistan's nuclear bomb, and the country's leading nuclear weapons facility, the Khan Research Laboratories, bears his name.

Eight scientists and administrators from the lab are currently in detention for "debriefings."

Pakistan's government denies it authorized any transfers of weapons technology to other countries — such as Iran, Libya or North Korea — but says individuals may have done so for their own profit.

Information Minister Sheikh Rashid Ahmed (search) said one KRL scientist, Saeed Mansoor Ahmad, was released late Saturday. He said the debriefings may end within a week.

An Interior Ministry official, speaking on condition of anonymity, said investigators were checking bank accounts of the detainees. He said investigators suspect that one scientist and one other person did something for personal gain, but would give no names or further details.

"Pakistan's investigations are vigorous. And they are looking into all dimensions, including financial aspects," Foreign Ministry spokesman Masood Khan told AP.