Washington is concerned that China's President Hu Jintao will give the green light to an ambitious expansion of China's controversial nuclear co-operation with Pakistan during his visit to Islamabad next week.

With the US Senate yesterday set to vote on the Bush administration's historic deal to legalise nuclear trade with India, an important step in the ending of a 30-year-old technology denial regime, any Chinese help to Pakistan could play into the hands of non-proliferation hawks on Capitol Hill.