Finnish authorities said Wednesday they have opened an investigation into the rupture of a data cable under the Baltic Sea, adding to a Swedish probe into the possible sabotage of that link and another cable.

An undersea data cable connecting Finland and Germany was cut in the early hours of Monday by what was likely an external impact and a nearby link between Lithuania and Sweden was also damaged.

German officials said on Tuesday they believe the damage to two underwater fiber-optic cables in the Baltic Sea was an act of sabotage, but they could not speculate beyond that.