Finland and Estonia on Friday signed an agreement to increase the security of their joint subsea infrastructure, which includes power and telecommunications cables, as well as the Balticconnector gas pipeline that was damaged a year ago.

Finnish police continue to investigate the pipeline incident while Estonian police lead the investigation of the simultaneous damage to subsea telecommunications links.

Police in both countries have yet to provide their conclusions.

"During the past few years we've noticed the concrete way that there is increasing threats for the security of the energy transfer routes, unfortunately, especially under the Finnish Gulf and overall in the Baltic Sea area," Mykkanen said.

Mykkanen said the enhanced cooperation meant that the two countries would join forces to boost technical surveillance, patrolling and repair capacities of the subsea infrastructure.