Jan. 27 (UPI) -- Swedish authorities boarded a vessel suspected of being involved in an earlier underwater sabotage of cables in the Baltic Sea on Monday.

In the latest incident of what officials are calling "gross sabotage," authorities said a communications cable between Sweden and Latvia was damaged on Sunday. The ship -- the Vezhen -- was escorted to Sweden's coast.

The suspected incident comes on the heels of other damage to undersea cables in the Baltic Sea followed by NATO announcing it was stepping up patrols to prevent such incidents from happening or at least capture suspects when they do.

"We suspect that a serious act of sabotage was committed in the Swedish economic zone yesterday," Swedish prosecutor Mats Ljungqvist said on Monday, according to The New York Times.

Sweden is one of NATO's newest members, joining with Finland after Russia's invasion of Ukraine. Some in NATO have blamed Moscow for damaging the underwater cables but the Kremlin has denied their involvement.

Latvia Prime Minister Evika Silina said NATO, Sweden and her country are working jointly to investigate the incident. Latvia state broadcaster LVRTC owns the damaged undersea cable. It said while they suffered "disruptions" in data transmissions, most of their customers were not affected.

On Jan. 14, NATO announced that it would beef up its patrol of the Baltic Sea in light of past cable and infrastructure damage on the seafloor. The Baltic Sentry program by the Allied Command Operations is responsible for deterring future attempts by state and non-state actors to damage underwater cables and other infrastructure.