MANILA: Three Chinese coast guard vessels were being monitored in the waters off remote islands in the northern Philippines near Taiwan, maritime officials in Manila said on Friday.

The vessels were first spotted on Thursday, a day after a YouTube video appeared in which Philippine President Ferdinand Marcos said there was no way Manila could stay out of conflict if China invaded Taiwan.

China considers self-ruled Taiwan to be part of its territory and has threatened to seize it by force.

The three Chinese vessels were spotted near Batanes province, a remote group of sparsely populated islets north of the Philippines’ largest island, Luzon.

An aircraft was deployed on Friday to monitor the “irregular movements” of the three Chinese ships near the Batanes islands, the Philippine Coast Guard said in a statement.