Pakistan's President Pervez Musharraf has said it appears that Pakistani scientists have sold nuclear secrets to other nations.
Musharraf insists there was no government involvement
But the president again stressed there was no government involvement.
Speaking to CNN at the World Economic Forum in Switzerland, he said: "It is clear it was done by individuals for their own personal financial gain."
The Pakistani leader also said that al-Qaeda could have been behind two recent attempts on his life.
Pakistan began an investigation into possible illegal transfers of nuclear technology to countries such as Iran more than a month ago.
It followed information provided by the International Atomic Energy Agency (IAEA).
So far more than a dozen people have been questioned, including the country's foremost nuclear scientist, Abdul Qadeer Khan.
Nine scientists and officials are still being held for questioning.
President Musharraf's comments in Davos went further than the previous government line that officials and scientists may have passed secrets out of personal greed and ambition.
He said he expected the probe to be finished in "a few weeks".
President Musharraf promised "stern action" against anyone found to have transgressed.
"There is nothing that we want to hide. We want to be very clear about it...
that we will move against anybody who proliferated," he said.
But he also stressed: "There is no evidence that any government personality or military personality was involved in this at all."
At least 15 people died in the second assassination attempt
The IAEA's chief, Mohamed ElBaradei, also in Davos, said: "I think what we know is that there have been individuals involved. I do not want to jump to conclusions and say a government is involved."
On the recent assassination attempts, President Musharraf said the al-Qaeda network was possibly behind them.
He told CNN that, while those directly involved had been rounded up, police were still trying to determine their links.
"We haven't yet got to the top of identifying the person who has issued the order, but we know there are linkages that maybe the idea came from al-Qaeda," General Musharraf said.
He was unharmed by the two bomb attacks on his motorcade, which came within two weeks of each other in December.
But at least 15 people were killed in the second attack, on Christmas Day.
On 14 December, a bridge was blown up seconds after his convoy had crossed it. No one was injured.
Both attacks took place near General Musharraf's military residence in the city of Rawalpindi.