China on Wednesday imposed sanctions on nine US defence firms, describing the measures as retaliation for arms sales to Taiwan.

"Weapons sales by the United States to China's Taiwan region have seriously violated the one-China principle... seriously infringed upon China's sovereignty and security interests, (and) damaged China-US relations," Foreign Ministry spokesman Lin Jian told a news conference.

"China strongly condemns and firmly opposes this and has lodged solemn representations with the United States."

Lin said Beijing was "taking resolute countermeasures" by imposing sanctions on nine US defence firms.

The steps taken against the firms, including Sierra Nevada Corporation and Stick Rudder Enterprises LLC, became effective on Wednesday.

Their assets in China would be frozen, and organisations and individuals within China are prohibited from engaging in transactions with the firms.

The countermeasures also applied to Cubic Corporation, S3 Aerospace, TCOM Ltd Partnership, TextOre, Planate Management Group, ACT1 Federal and Exovera. (Agencies)