As the Philippines seeks deeper cooperation with the Taiwan authorities under the pretext of protecting undersea cables, Foreign Ministry spokeswoman Mao Ning said "there is no gray area on the Taiwan question".

At a daily news briefing in Beijing on Thursday, a reporter asked whether China believes such cooperation violates the one-China principle.

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In response, Mao said, "There is no gray area on the Taiwan question. The Philippine side should uphold the one-China principle with concrete actions."

"China's Taiwan region should strictly adhere to the one-China principle when conducting exchanges with foreign countries," she added.