Finnish authorities boarded and seized a cargo vessel called Fitburg, after it was suspected of having damaged underwater cables in the Baltic Sea, Finnish police told a press conference.
The vessel sailed under the flag of St Vincent and Grenadines, a police spokesperson said.
The vessel had departed from St Petersburg in Russia and was headed to Haifa in Israel, according to Marine Traffic data.
Fourteen crew members are being held by Finnish police, and come from Russia, Georgia, Kazakhstan and Azerbaijan.
"Finnish authorities have taken control of the vessel as part of a joint operation," police said, adding they were investigating the case as aggravated criminal damage.
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 Sea with frigates, aircraft and naval drones in recent years. A spokesperson for the military alliance declined to comment on the incident.
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 said.
The cable belongs to Finnish telecoms group Elisa.
"At this stage, the police are investigating the incident as aggravated criminal damage, attempted aggravated criminal damage, and aggravated interference with telecommunications," police said.
'Hopefully not deliberate,' says Estonian President
Estonia's justice ministry said a second telecoms cable connecting the country to Finland had also suffered an outage today.
It was not immediately clear if the cable, belonging to Sweden's Arelion, was running parallel to Elisa's.
"I'm concerned about the reported damage ... Hopefully it was not a deliberate act, but the investigation will clarify," Estonia's President Alar Karis said on X.
Finland's President Alexander Stubb said on X that he was monitoring the situation.
"Finland is prepared for security challenges of various kinds, and we respond to them as necessary."
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.
