Taiwan's coast guard said on Monday that it had disrupted "illegal" operations by a Chinese research ship in waters close to the island and driven it away, part of what Taipei sees a provocative pattern of China's stepped up maritime activities.
The coast guard said that last Thursday it detected the Chinese ship the "Tongji", which was commissioned only last year, 29 nautical miles southeast of the southern tip of Taiwan though just outside restricted waters.
The ship was observed lowering ropes into the water, suspected to be the deployment of scientific instruments for "illegal" survey operations, and the coast guard sent its own ship in, it said in a statement.
The Taiwanese ship moved in close to create wake interference, and broadcast messages to "forcefully expel the vessel, prohibiting it from conducting related activities".
The "Tongji" then retrieved its survey instruments and altered course, departing from Taiwan's waters, the coast guard said.
China's Taiwan Affairs Office did not immediately respond to a request for comment.
Taiwan's coast guard said it continued to shadow the Chinese ship until Monday, when it proceeded away from waters close to the island.
"Chinese research vessels, in disregard of international law, have attempted to conduct illegal survey activities in our waters," it said, calling on China to stop such practices.
Chinese state media says the "Tongji" has all-weather operational capability and can carry remotely operated vehicles, laboratories and unmanned systems.
It can be used for marine geology, oceanography, marine chemistry and marine biology research, and is capable of performing offshore engineering operations such as pipeline laying, Chinese media have reported.
As well as regular Chinese military activities around Taiwan, which views the island as its own territory, Taiwan has also complained that China regularly sends ostensibly civilian ships into its waters as part of "grey zone" harassment designed to pressure Taipei and exhaust its forces.
