The mainland firmly opposes any form of official exchanges or military ties between the United States and Taiwan after a US Navy research vessel docked at Kaohsiung in southern Taiwan on Monday, a mainland official said on Wednesday.

"Our position is consistent and clear as always," Ma Xiaoguang, spokesperson for the Taiwan Affairs Office of the State Council, told a regular news conference.

The island's "military authorities" said on Tuesday that the US vessel is unrelated to military activity, and it is visiting Taiwan for joint scientific research with a Taiwan university.