China is providing assistance to Pakistan in developing its plutonium-based nuclear weapons programme, a Congressional report has told US lawmakers.      

Besides the conventional uranium-based nuclear weapons, Pakistan has also pursued plutonium-based warheads since the 1990s and continues to produce plutonium for weapons, the Congressional Research Service (CRS) said in latest its report on the country's nuclear programme.      

"Pakistan has received Chinese assistance for its plutonium programme," said the report by CRS, the research wing of the Congress that regularly prepares reports in issues of interest by the US lawmakers.      

"It appears that Islamabad is constructing two additional heavy water reactors, which will expand considerably Pakistan's plutonium production capacity, at the same site," the report said.