NATO is ratcheting up its guard against suspected attempts to sabotage underwater energy and data cables and pipelines that crisscross the Baltic Sea.

Swedish authorities boarded a Maltese-flagged ship seized in connection with the latest breach of cables running along the bottom of the Baltic Sea to begin an investigation into the matter, the country's security police said on Monday.

Cables deep under the Baltic Sea keep getting damaged - here is what Nato is doing to protect them - Nato is deploying eyes in the sky and on the Baltic Sea to protect cables and pipelines

After a series of suspected undersea cable cuttings, NATO has launched a new surveillance and deterrence mission to protect critical infrastructure under the Baltic Sea.

The Nordic country has opened an investigation into the damage, just weeks after NATO stepped up its military presence in the area following a series of similar incidents.

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