Amid reports of involvement of top Pakistani scientist, A Q Khan, in alleged transfer of nuclear technology to other nations, a senior minister has defended him, saying the architect of the country's nuclear programme in not a suspect.

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"There is no evidence against Dr A Q Khan and he is not a suspect as yet," Interior Minister Faisal Saleh Hayat was quoted as saying by The Nation daily on Friday.

With a number of reports in a section of media implying Khan's link in nuclear proliferation, Hayat said: "It is premature to term Dr Khan a suspect."

The government, he said, is debriefing some nuclear scientists because it wants to get to the bottom of the allegations of nuclear proliferation.

"We are questioning a number of scientists and some of them are suspects, but Dr Khan is not amongst them," he said.

Hayat said Khan is not under arrest and is free to move at will. "If there is any requirement, Dr Khan will definitely cooperate with the government."

Expressing disappointment over the failure of some European countries to investigate the involvement of their own scientists in nuclear proliferation, he said Pakistan is "upset" with casual handling of allegations of proliferation.

Pakistan's investigation into the alleged leaks was launched after the UN's International Atomic Energy Agency wrote to the government in November relaying information provided by Tehran about the alleged sales of nuclear know-how.

The letter mentioned names of some Pakistani scientists suspected of selling nuclear know-how for personal profit.