ISLAMABAD, Jan 22: Pakistan investigators visited Iran and Libya late last year to investigate allegations that Pakistan scientists sold nuclear secrets to the so-called "rogue states," Information Minister Sheikh Rashid Ahmad said here on Thursday.

The two separate visits preceded the current probe into 13 top nuclear scientists, engineers and administrators, including Dr Abdul Qadeer Khan. The inquiry visits were prompted by a letter in November from the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), Mr Rashid added.

"After the IAEA inquiries they wanted to have themselves some information against some people," the minister said. The IAEA letter came after almost a year after the US media reports quoting unnamed US, European and Middle East officials accusing Pakistan of being the source of leakages of nuclear weapons technology to Iran, North Korea and more recently Libya.

Mr Rashid said he did not know who was in the team or how large it was. "They wanted to check how much involved (the scientists and engineers) were, whether they were involved or not."

Asked what they were alleged to be involved in, Mr Rashid said: "something like information leakage." The minister would not say when the trip took place, but it appears to have been between the receipt of the IAEA letter in November and the first interrogations of nuclear scientists in December.

Four scientists - Mohammad Farooq, the director of Pakistan's key uranium enrichment plant A.Q. Khan Research Laboratories, were detained for debriefing in December. Another 8 scientists were detained at the weekend.

Even Mr Khan himself, an official national hero, was also debriefed though not in custody. A senior government official, who requested anonymity, said investigators first went to Vienna, Austria, where the IAEA is headquartered.

"Pakistan sent a small team of technical officials first to Vienna, then to Iran after which they launched the debriefing of four scientists in the first week of December," the official told AFP.-Agencies