Islamabad: Washington accused Pakistan's largest nuclear facility of sharing technological know-how to make weapons of mass destruction or missiles capable of delivering them, a US Embassy spokeswoman said. Islamabad said the allegation was "baseless".

Linda Cheatham said on March 31 that another "country, person or entity" was involved in the technology transfer and refused to say which. But a North Korean firm, Changg Wang Sinyong Corp, was also slapped with sanctions, apparently for its alleged role in missile transfers with Pakistan.

On April 1, Pakistan demanded Washington provide proof.

"This is absolutely baseless. We ask America to come up with whatever evidence they have to prove what they are saying," Information Minister Sheikh Rashid Ahmed said.