Western countries did not 'actively oppose' Pakistan developing its nuclear weapon in the late 1980s as they were "too scared" and pre-occupied with the Russian invasion of Afghanistan and its future consequences, disgraced atomic scientist A Q Khan has said.

Khan, who has been slapped sanctions by the US for running a clandestine nuclear network, also said the West ignored Pakistan's nuclear program as it needed the country's support to push the then Soviet Russia out of Afghanistan.

"The Afghan War was a blessing for our nuclear programme," Khan said in an interview to the Newsweek's inaugural Pakistani edition.

"It was not that the Western countries actively supported it but that they were too scared and (pre) occupied with the Russian invasion of Afghanistan and its future consequences to actively oppose it," he said.