The United States has sought to disprove Pakistan President Pervez Musharraf's claim that it had not given him 'convincing proof' about Abdul Qadeer Khan's nuclear proliferation activities.

The state department on Tuesday night said it had provided 'pieces of information' from time to time as part of the 'ongoing dialogue' on the issue.

"We have talked to them at different moments about different issues that might have arisen that we might have learned about. So it is not a single moment of information," state department spokesman Richard Boucher said.

"It was rather an ongoing dialogue that covered both the general concerns that we have had about possibilities, and then from time to time, pieces of information that related to different aspects of things that we might have encountered or known were going on," he said.

In an interview with the New York Times on Monday, Musharraf shared blame for the delay with Washington saying it was not until October that American officials provided him with evidence of the activities of Khan.

But Boucher said the US non-proliferation dialogue with Pakistan certainly goes back much farther than October (when Deputy Secretary of State Richard Armitage went to Pakistan).

"What I would say is that we have had longstanding concerns about proliferation that could come from Pakistan. We have discussed non-proliferation issues with Pakistan repeatedly over a long period of time and it has been an issue of concern to us and President Musharraf as well," he said.

Also Read We knew of A Q Khan's indiscretion, admits Powell I suspected Khan for three years: Musharraf I faced a dilemma pardoning Khan: Musharraf Special: Khan's colleagues turned him in

Boucher said that he was not in a position to go into what the department said to the Pakistan Government at different times, because 'that gets into what we knew at different times about activity that was going on'.

"Once again, I'd say that Pakistan has taken the matter seriously over time and particularly with regard to the current investigation and what they are doing to make sure that Pakistan is not a source of proliferation," he said.

"We welcome that progress and will continue to work with Pakistan as Pakistan investigates and also works itself with the international community," he added.

At this point, said Boucher, the investigation is still ongoing. "I believe they shared some information with the international community, with the International Atomic Energy

Agency, but I am not in a position to describe the results of their investigation. Obviously, they are the ones to do that when it is appropriate," he said.

"We have seen a series of commitments from Pakistan," said Boucher. "I refer specifically to the ones in October of 2002 when President Musharraf made clear that he did not want Pakistan to be a source of proliferation activity, and then steps such as the current investigation that he has taken to make sure that did not occur," he said.

Meanwhile, White House Press Secretary Scott McClellan at a briefing said, "We certainly value the assurances that President Musharraf provided. But proliferation is a very serious matter."

"It is a very high priority for this administration," he said. "In a post-September 11 world it is important that we do everything we can to stop proliferation of weapons of mass destruction."

"That is why the president launched the proliferation security initiative to work with other nations to interdict shipments of weapons of mass destruction and to stop the proliferation of weapons of mass destruction. That is why the president is working closely with other nations to stop production of weapons of mass destruction," Scott said.

Pakistan's Nuclear Bazaar