The United States claims Dr Khan headed a network of nuclear proliferators and some US politicians want to question him over his alleged involvement in providing nuclear know-how to Iran, Libya and North Korea.
He was placed under house arrest after the unearthing of the alleged network but was released in early February.
‘Khan is again a loose nuke scientist with proven ability to sell the worst weapons to the worst people,’ said Democratic Congresswoman Jane Harman, a lead author of the bill.
The legislation would also tie continued US military aid to assurances from Islamabad that it is monitoring Dr Khan’s movements and activities.
‘Hopefully, appropriate Pakistani officials worry as we do that their civilians could become nuclear targets — as could Nato soldiers in neighbouring Afghanistan or civilians in any number of Western countries,’ said Rep. Harman.
The United States had stopped military and economic assistance to Pakistan in 1990, following a dispute over its nuclear programme.
Diplomatic observers in Washington, however, say that it would be difficult to bring such sanctions against Pakistan at this stage when the United States wants the allied nation to increase its role in fighting terrorism.
Pakistan is already resisting Washington’s offer for greater US involvement in training the Pakistani military.
Senior US officials and lawmakers — such as Vice President Joe Biden and Senator John Kerry, who heads the powerful Senate Foreign Relations Committee — have described the previous sanction against Pakistan as a mistake and opposed any future sanctions.
US officials say that the previous sanction, known as the Presslar Amendment, reduced their influence in Pakistan, particularly in the military, and has left bitter memories in that country.