Three Chinese government ships entered Japanese territorial waters Friday, the coastguard said, days after Japan's premier vowed to expel any Chinese landing on a chain of disputed islands.
The maritime surveillance ships entered the 12-nautical-mile zone off the Senkaku islands, which China calls the Diaoyu, around 10:00 am (0100 GMT), the Japanese coastguard said in a statement.
On Tuesday, eight Chinese government vessels sailed into the disputed waters, the biggest flotilla to sail there in a single day since Tokyo nationalised part of the island chain in September.
The move sparked an angry response from Tokyo, with Japanese premier Shinzo Abe vowing to "expel by force" any landing by the Chinese on the archipelago, which is believed to harbour vast natural resources below its seabed.
Abe's comments came as China and South Korea launched diplomatic protests over a visit by nearly 170 Japanese lawmakers to the controversial Yasukuni war shrine in central Tokyo, seen as a potent symbol of Japan's imperialist past and wartime aggression.
Since the nationalisation, state-owned Chinese ships have frequently spent time around the five disputed islands, also claimed by Taiwan.