The US has already voiced its disapproval before the meeting, which starts today, and will try to forge a consensus on updating the rules designed to prevent the spread of nuclear weapons.
US officials say that the plan requires special exemption from the NSG, which China joined in 2004, as Pakistan has not signed the Nuclear Non-Proliferation Treaty and could, therefore, divert some technology to its nuclear weapons programme or to another country.
China and Pakistan disagree, pointing out that the US set a precedent by sealing a deal to sell civilian nuclear fuel and technology to India in 2006, even though Delhi had yet to sign the treaty.
That deal, which lifted a US ban imposed after India tested its first nuclear device in 1974, was seen as the cornerstone of a new partnership with Delhi designed to counterbalance Chinas influence in Asia. However, critics say that it undermined the international non-proliferation regime.
Having muscled the Indian deal through the NSG in 2008, the US is likely to struggle to forge a consensus against Chinas deal with Pakistan. Because Washington pressed the NSG and China to exempt India from NSG trade sanctions, it is now more difficult to complain about Chinas desire to export reactors to Pakistan, said Mark Hibbs, a nuclear expert at the Washington-based Carnegie Endowment for International Peace.
The dispute could also complicate US-led efforts to prevent Iran from developing a nuclear bomb, since any multilateral action requires Chinas support in the UN Security Council.
China has had close relations with Pakistan since the 1960s and had already built one reactor and started a second at Chashma, in Punjab, before joining the NSG. It signed the deal to build another two reactors at Chashma in February but is expected to argue that it does not need NSG exemption as it was already agreed before 2004.
The US did not protest when the deal first came to light but, after intense lobbying from India, it said last week that it had asked China to clarify the details.
The US sees Pakistan as a key ally in the war against al-Qaeda and the Taleban, but has grave concerns about proliferation especially since Abdul Qadeer Khan, Pakistans top nuclear scientist, confessed in 2004 to selling nuclear secrets to North Korea, Iran and Libya.
Washington also worries about the potential for Islamic militants to attack or capture Pakistani nuclear sites. Last year Pakistani police said that they found a map of Chashma in the possession of five American Muslims arrested for plotting a terrorist attack.
China responded to the US statement last week by insisting that its nuclear cooperation with Pakistan was for peaceful purposes and under the supervision of the International Atomic Energy Agency.
Pakistan said that the deal was needed to help to ease chronic power shortages that have caused long blackouts across the country for much of this year.(The Times)