The United States on Monday announced sanctions on disgraced Pakistani scientist A Q Khan and 12 other individuals for their involvement in clandestine nuclear proliferation network providing atomic weapon designs and technology to North Korea, Iran and Libya.
"The Department of State announced that sanctions will be imposed on 13 individuals and three private companies for their involvement in the A Q Khan nuclear proliferation network," the spokesman's office said in a statement in Washington.
The sanctions were announced after a 'multi-year US government review of the available information pertaining to the activities of this network', it said.
Khan, 68, led an 'extensive international network for the proliferation of nuclear equipment and know-how that provided 'one stop shopping' for countries seeking to develop nuclear weapons', the office of the State Department spokesman said in a statement in Washington.
The US said it believes the sanctions will 'help prevent future proliferation-related activities by these private entities and provide a warning to other would-be proliferators'.
Khan has been kept under house arrest in Islamabad since 2004, when he confessed on state television to have leaked atomic secrets to countries including Iran and Libya. The scientist retracted the statement after four years, saying he was made to confess under duress.
Khan and his associates provided Iran and Libya with centrifuge components, designs, and, in some cases, complete centrifuges, the State Department said.
"The United States also believes that Khan and his associates provided centrifuge designs, equipment, and technology to North Korea. Dr Khan also provided Libya with nuclear weapon designs," it said.
With the assistance of Khan's network, countries could leapfrog the slow, incremental stages of other nuclear weapons development programmes, it added.
In 2004, following Libya's decision to renounce its nuclear programme, the US removed from Libya items it had received from the network.
The network's actions have irrevocably changed the proliferation landscape and have had lasting implications for international security, the US said.
Many of Khan's associates are either in custody, being prosecuted, or have been convicted of crimes, it noted.
"While we believe the A Q Khan network is no longer operating, countries should remain vigilant to ensure that Khan network associates, or others seeking to pursue similar proliferation activities, will not become a future source for sensitive nuclear information or equipment," the statement said.