The Chinese activities off Taiwanâs Pacific coast have triggered concern from some Western countries, which have warned against any unilateral change to the status quo or actions that could raise tension in the Taiwan Strait.

In a statement, Chinaâs coast guard said the patrols east of Taiwan were led by one of its ships, Xiushan, and it would continue to strengthen such efforts.

âSince July, the Xiushan task group had been strengthening control over the relevant waters to effectively ensure orderly navigation and activities,â its spokesperson, Jiang Lue, said.

The effort was safeguarding the legitimate and lawful rights and interests, as well as the lives and property of fishermen on both sides of the Strait, he added.

Taiwanâs Coast Guard Administration said a patrol ship, the Taipei, was among the vessels it sent to monitor the Chinese ships, and accused Beijing of engaging in âfake law enforcement, real expansion of powerâ.

Two Chinese coast guard vessels, the Xiushan and Chongming, were detected on Friday, it said.

One drifted about 151 nautical miles east of Lanyu, also known as Orchid Island, and the other about 43 nautical miles to the islandâs northeast, it said, adding that Taiwan vessels were monitoring them.

It vowed to âtake all necessary measures to defend national sovereigntyâ and ensure the security of Taiwanâs waters.

China claims democratically governed Taiwan as its own territory, despite Taipeiâs rejection of Beijingâs sovereignty claims. Taiwan says only its people can decide their future.

China has stepped up military and coast guard activity around Taiwan, including operations to the islandâs east, on its Pacific side, an area Taiwan sees as vital for wartime supply lines from allies.

This week, the United Statesâ de facto embassy in Taiwan made a rare public disclosure of coordination between their coast guards.

It released a picture of a Taiwan coast guard vessel sailing in formation with the U.S. Coast Guard cutter Midgett at an unspecified location.

(Reporting by Liz Lee, Yimou Lee and Shanghai newsroom; Editing by Tom Hogue and Clarence Fernandez)