Swedish authorities say they are investigating a damaged cable that was discovered in the Baltic Sea, the latest in a string of recent incidents of ruptured undersea cables that have heightened fears of Russian sabotage and spying in the region.

Swedish police said on Friday they were investigating a suspected case of sabotage of an undersea telecoms cable in the Baltic Sea, and the country's coast guard deployed a vessel to the area where multiple seabed cables have been damaged in recent months.

The authorities are looking into possible damage to an undersea line east of Gotland island. NATO has stepped up its surveillance of the region.