The United States Congress, under the Taiwan Relations Act, requires the supply of weapons to the self-governing democracy for its defence.

US administrations had done so through sales rather than direct aid, but in August Washington for the first time approved direct US military aid to Taiwan under an assistance programme aimed at foreign governments.

"Despite China's firm opposition, the US government is determined to provide weapons to Taiwan... seriously harming China's sovereignty and security interests, and going further and further on the wrong and dangerous road of arming Taiwan," Chinese foreign ministry spokeswoman Mao Ning said at a regular press briefing.

She said that Lockheed Martin was the prime contractor in US arms sales to Taiwan that took place on August 24, and that Northrop Grumman had taken part in sales "many times".

"According to the Anti-Foreign Sanctions Law of the PRC, China has decided to impose sanctions on the above two US military companies," she said.