The Philippines said Sunday it had deployed a coast guard ship to challenge Chinese patrol boats attempting to "alter the existing status quo" in the disputed South China Sea.

Beijing claims most of the strategic waterway despite a 2016 international tribunal ruling that went against it, and there have been frequent clashes and tense standoffs between Philippine and Chinese vessels.

Brunei, Malaysia, Taiwan, and Vietnam also have claims to the waters.

Commodore Jay Tarriela, Philippine Coast Guard (PCG) spokesperson for the West Philippine Sea, said Chinese patrol ships had come as close as 60 nautical miles (111 kilometers) west of the main Philippine island of Luzon this year.

"Their goal is to normalize such deployments, and if these actions go unnoticed and unchallenged, it will enable them to alter the existing status quo," he said in a statement.

He later told reporters that Manila had deployed a coast guard ship to the area to challenge the "unlawful" Chinese patrols.

He said the deployment aimed to ensure Chinese patrols "are not normalized, and that this bullying behavior does not succeed."

Tarriela said the Chinese coast guard deployed three vessels from its Guangdong and Hainan bases to Philippine waters between 30 December and 11 January.

The South China Sea confrontations have sparked concern that they could draw the United States, Manila's long-time security ally, into an armed conflict with China.