A submarine cable was damaged in the Baltic Sea, the fourth case reported by the Nordic countries in the past two months. View on euronews

Swedish authorities have seized a ship over the “aggravated sabotage” of an undersea fibre-optic cable linking Latvia with a strategically important island in Sweden.

Swedish authorities boarded a vessel suspected of being involved in an earlier underwater sabotage of cables in the Baltic Sea on Monday.

Sweden has opened a preliminary investigation into suspected aggravated “sabotage” and ordered the detention of a vessel in the Baltic Sea suspected of damaging an underwater fiber optic cable connecting Latvia and the Swedish island of Gotland

The Arelion submarine cable, which connects the Swedish island of Gotland to Lithuania, and the C-Lion 1 submarine communications cable that runs between Finland's capital Helsinki and the German city of Rostock were also damaged in mid-November near Sweden's territorial waters.

Hundreds of Swedish troops arrived in Latvia on Saturday to join a Canadian-led multinational brigade along NATO's eastern flank, a mission Sweden is calling its most significant operation so far as a member of the Western defense alliance.

The undersea cable is based in the Baltic Sea, and may have been deliberately damaged on Sunday, according to officials in Sweden.

A subsea data cable between Latvia and Sweden was damaged early Sunday, sparking a criminal investigation, a third such incident in the Baltic Sea in the past three months.

Mads Petersen, owner of Greenland-based startup Arctic Unmanned, sat in a car to keep warm while he tested a small drone at minus 43 degrees Celsius (minus 45 degrees Fahrenheit). The cold soon drained the drone’s power.

Several undersea cables running under the surface of the Baltic Sea have been damaged in suspected sabotage incidents in recent months.

On Sunday, an undersea cable ferrying data between Sweden and Latvia was damaged, most likely as a result of an external force, Latvia said.