China has said its civilian nuclear co-operation with Pakistan is peaceful.
A spokesman for the Chinese foreign ministry said its plan to provide Pakistan with two new reactors was in line with international obligations.
Earlier this week, the United States expressed concern at the deal.
Fears over Pakistan's nuclear activities rose in 2004 after a top scientist admitted leaking nuclear technology to North Korea, Libya and Iran.
Relations between Pakistan and its neighbour India are also of continuing concern. Both are nuclear-armed.
