Islamabad: Pakistan's top scientist Abdul Qadeer Khan, involved in clandestine nuclear sales to "rogue States", has reportedly suffered a heart attack.

"Dr Khan is under treatment at his residence and his condition is stated to be critical," a local daily quoted officials of the hospital of the country's premier nuclear installation, Khan Research Laboratories (KRL), formerly headed by Khan, as saying.

It said in view of his "poor cardiac" condition, a heart specialist along with a cardiac machine was "secretly" sent to the nuclear scientist's residence.

Khan had been suffering from pain in his left hand since he was questioned by intelligence agencies for the past few months for his alleged involvement in transferring nuclear technology, 'The Dawn' daily said.

He met President Pervez Musharraf a fortnight ago and admitted his guilt. He confessed about his involvement in nuclear proliferation over State television after which he was pardoned by the military ruler.

The newspaper said Khan had never suffered from cardiac complaint before the incident, but he often felt pain in his left hand whenever he took extra burden and pressure of official work.

"Dr Khan was holding his left hand when he was shown the last time on television after his meeting with President Gen Pervez Musharraf," it said, adding he had been placed in either "protective custody or house arrest since December and that he had been asked to avoid appearing at public places and functions".

Khan has also been prohibited from attending telephone calls and speaking to the media, the paper said.

The newspaper also quoted some family members of the other KRL nuclear scientists and officials as saying that the condition of Khan and his Dutch wife Hamdarina was "bad".

"Both of them are suffering from high blood pressure and they have been given potency doses by the doctors of the KRL hospital," it said.

The newspaper also said Pakistan's Defence spokesman Maj Gen Shoukar Sultan and senior director of KRL hospital, Ali Raza Kazmi, refused to comment on the condition of Khan.

Pakistan Government has detained 11 KRL scientists and officials in connection with allegations of proliferation of nuclear technology to Libya, North Korea and Iran.