BEIJING - A Chinese mainland spokesperson on Saturday expressed firm opposition to the visits by some US Congress members to China's Taiwan region in so-called "unofficial" capacities.

These acts have seriously violated the one-China principle and the provisions of the three China-US joint communiques, said Ma Xiaoguang, a spokesperson for the State Council Taiwan Affairs Office, in response to US Senator Marsha Blackburn's visit to Taiwan from Thursday to Saturday.

The spokesperson warned Taiwan's Democratic Progressive Party authorities that their attempts to draw in external anti-China forces to make provocations seeking "independence" are doomed to failure.