China has protested against a US decision to sell $6.4bn worth of weapons to Taiwan, saying it would cause "serious damage" to relations and co-operation between the two nations.
A spokesman for the Chinese embassy in Washington said Beijing sent an urgent petition in the early hours of Saturday and also made its displeasure known when US officials spoke to a Chinese diplomat to unveil the decision.
The sale "constitutes a gross intervention into China's internal affairs, seriously endangers China's national security and harms China's peaceful reunification efforts," Wang Baodong, a spokesman for the Chinese embassy in Washington, quoted He Yafei, the Chinese vice foreign minister, as saying.
"The US plan will definitely undermine China-US relations and bring about serious negative impact on exchange and co-operation in major areas between the two countries," he said, adding that "China strongly urges the US side to fully recognise the gravity of the issue, revoke the erroneous decision on arms sales to Taiwan and stop selling any weapons to Taiwan".
In 2008, China suspended most military dialogue with Washington after the administration of George Bush, the former president, approved a $6.5bn arms package to Taiwan that included guided missiles and attack helicopters.
Beijing regards Taiwan as a renegade province and has vowed to bring the island eventually back under mainland rule, by force if necessary.
The US government, on the other hand, is bound by the 1979 Taiwan Relations Act which obliges Washington to ensure the island is capable of responding to Chinese threats, and to sell defensive weapons to it.
Wang said that the weapons deal violated the 1982 communique between China and the United States, which said the arms sales to Taiwan "will not exceed, in qualitative or in quantitative terms," the level in the years before that.
Philip Crowley, a state department spokesman, said that the arms sales were consistent with the three key communiques between the United States and China when they normalised relations.