Pakistani officials are calling a report about Abdul-Qadeer Khan in Time Magazine baseless.
Information Minister Sheikh Rashid Ahmed says there is no evidence to support the article's claim that Mr. Khan's network may have sold weapons material or know-how to Saudi Arabia and Egypt, or to al-Qaida and other non-state groups.
But he admitted that investigators may still not know the full extent of the Khan network.
Pakistani Foreign Ministry spokesman Masood Khan also disputes the report's suggestion that Pakistan is ignoring such evidence or is insensitive to international concerns about the case.
"I think that this is just rubbish. There is no substance in it," he commented.
Last year, A.Q. Khan, the former supervisor of Pakistan's successful nuclear weapons program, admitted to having sold technology and material to North Korea, Libya, and Iran.
But the Foreign Ministry spokesman says Time's suggestion that Pakistan is not doing enough to investigate possible links to other countries or to terror groups is merely a re-hash of sensationalistic statements and not based on fact.
"This is a story that sells, I mean from a purely commercial point of view. But most of the stories which have appeared lack credibility. … The sources quoted in this very story are suspect," he said.
The Time article quotes numerous unnamed sources from the United States and Libya, as well as a source described as an acquaintance of A.Q. Khan.
The report also refers to Pakistan's refusal to allow U.S. investigators to question Mr. Khan personally.
But U.S. Ambassador to Pakistan Ryan Crocker told VOA earlier this month that he does not see this as a major issue, so long as Pakistani authorities are continuing their investigation.
"It is more important that the questions be asked and continue to be asked until there are satisfactory answers. I think it is less important who is asking the questions," said Ambassador Crocker.
He said that Pakistan is still looking into Mr. Khan's international nuclear black-market operation and has promised to share its findings with Washington.