"Finnish authorities have taken control of the vessel as part of a joint operation," the police said, declining to name the ship or its nationality, or give any further details about the vessel and its crew.
Eight NATO states border the Baltic Sea, which also borders Russia. They have been on high alert after a string of outages of power cables, telecoms links and gas pipelines that run along the relatively shallow seabed since Russia invaded Ukraine in 2022.
NATO has boosted its presence in the Baltic with frigates, aircraft and naval drones.
The vessel suspected of causing the latest damage was dragging its anchor in the sea, and was directed to Finnish territorial waters, the police and Finland's Border Guard authority said. The cable belongs to Finnish telecoms group Elisa, police said.
Finland's President Alexander Stubb said he was monitoring the situation. "Finland is prepared for security challenges of various kinds, and we respond to them as necessary," he wrote on X.
Finland in December 2024 boarded the Russian-linked oil tanker Eagle S which investigators said had damaged a power cable and several telecoms links in the Baltic Sea by dragging its anchor.
A Finnish court in October dismissed a criminal case against the Eagle S captain and other crew members, ruling prosecutors failed to prove intent and that any alleged negligence must be pursued by the ship's flag state or the crew's home countries.
