Downplaying concerns that Pakistani scientists were involved in nuclear proliferation, the US has said it welcomed Pakistan's commitment to conduct an investigation into the affair and that President Pervez Musharraf has given an assurance that such activities were 'part of the past'.

"We welcome the investigations the Pakistani government is conducting. We think they've shown how high a priority it is for the Musharraf government to make sure that Pakistan is not cooperating in any way or that Pakistan's sensitive nuclear assets don't fall into the wrong hands. So that is something we have been welcoming," state department spokesman Richard Boucher said on Wednesday.

He was replying to questions on Islamabad's investigation into alleged nuclear proliferation by its scientists, including father of Pakistan's bomb Abdul Qadeer Khan, to Iran, Libya and other countries.

"I think that we have seen a very firm commitment from President Musharraf on making sure that their assets and expertise don't fall into the wrong hands and we now see them conducting an investigation. So I can't draw conclusions yet, but that is the kind of commitment that we have seen," Boucher said.