BEIJING, Jan. 15 -- A Beijing spokesman on Wednesday said that the mainland and Taiwan should work together to safeguard China's sovereignty over the Diaoyu Islands.

"People across the Taiwan Strait should bear responsibility for China's sovereignty and territorial integrity," said Ma Xiaoguang, spokesman for the Taiwan Affairs Office of the State Council.

Relations between China and Japan soured after Tokyo's unilateral "nationalization" of some of the islands in September 2012.

Ma reiterated China's stance that the islands have been Chinese territory since ancient times.

People across the Taiwan strait, as well as the international community, are clearly aware of Japan's deliberate provocating disputes, intensifying conflicts over the islands, and threatening regional peace and stability, Ma added.