Japan’s foreign minister has warned that ties with China are “significantly deteriorating”, after Chinese vessels repeatedly entered disputed waters in the East China Sea.
Fumio Kishida said he had called China’s ambassador to protest against the “incursions”.
On Friday, about 230 Chinese fishing boats and coast guard vessels sailed near islands claimed by both countries.
Beijing has been increasingly assertive about waters it believes are Chinese.
The Japan-controlled, uninhabited islands – known as the Senkaku in Japan and the Diaoyu in China – are the source of a long-running dispute.
The Japanese coast guard said on Monday that about 13 Chinese coast guard ships, some of them armed, had been seen near the islands, higher than the usual number.