The Silver Dania cargo ship was seized at the request of Latvian authorities, and with the help of Norway's coast guard, police in the northern Norwegian city of Tromsoe said on Friday.
"It is suspected that the ship has been involved in serious damage to a fibre cable in the Baltic Sea between Latvia and Sweden," the police said in a statement.
The Silver Dania's owner, the Silver Sea shipping group, denied that the vessel was involved in the undersea fibre optic cable damage, Norwegian broadcaster TV2 reported.
Sweden and Latvia are investigating the suspected sabotage on Sunday of the cable linking the two countries, and Swedish police seized and boarded Maltese-flagged cargo ship Vezhen on suspicion it caused the damage.
Norwegian police said the two ship seizures were related to the same incident.
"The suspicion is that someone on the (Silver Dania) has something to do with the cable incident," police lawyer Ronny Joergensen told a press conference. He declined to provide detail.
The Baltic Sea region is on high alert after a string of power cable, telecom link and gas pipeline outages since Russia invaded Ukraine in 2022, and the NATO military alliance recently boosted its presence with frigates, aircraft and naval drones.
Mats Ljungqvist, the Swedish prosecutor handling the sabotage investigation in Sweden, said he now had a clearer picture of what happened and that he believed that the Vezhen had caused the cable damage.
"Our view is that it is the vessel that we have seized that has caused the cable break," he told Reuters.
"We have looked at the vessel that has been seized in Norway but for various reasons we have dismissed it."
He declined to comment further on the investigation, citing confidentiality.
The head of the Bulgarian company that operates the Vezhen said on Monday it might have struck the Baltic undersea cable with its anchor but denied any malicious intent. The company did not immediately respond to a request for comment on Friday.
The ship that was seized in Norway was Norwegian owned and flagged, and had been sailing from St. Petersburg in the Baltic Sea to Murmansk in the Russian Arctic, police said.
The owner and crew of the Silver Dania had voluntarily agreed that it would follow a coast guard vessel to port, the police added.
