China's government said on Wednesday that a Chinese man arrested near Taipei after crossing the Taiwan Strait on a speedboat was acting on his own and that Taiwan should not be so suspicious, in a case that has alarmed Taiwanese security officials.

Taiwan's coast guard arrested the man on Sunday in the coastal neighborhood of Tamsui after his boat entered a river that leads into Taipei amid ongoing tensions between Taiwan and China.

Taiwan says the man is a former Chinese navy captain who could have been probing the island's defenses.