The US sharply stepped up its criticism of China at the weekend, questioning the motives behind a Chinese military build-up, calling on the country's Communist rulers to embrace “a more open and representative government” and urging Beijing to do more to persuade North Korea to abandon nuclear weapons.

Donald Rumsfeld, US defence secretary, said the Pentagon's 2005 report on the Chinese military, to be published soon, concluded that China's defence spending was much higher than officially admitted, with its military budget ranking highest in Asia and third in the world.