Swedish and Finnish police are investigating a suspected case of sabotage of an undersea telecoms cable in the Baltic Sea, and Sweden's coast guard has 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.

Swedish authorities said on Friday they were 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.