Damage to the Balticconnector pipeline and a telecommunications cable was confirmed on Tuesday after one of the two pipeline operators, Finland’s Gasgrid, noted a drop in pressure and possible leak on Sunday night during a storm.

Finland, which is investigating, has said the damage was probably caused by “outside activity”, renewing concern over regional energy security and pushing gas prices higher just over a year after the dramatic Nord Stream pipeline bombings.

“Involvement of a state actor in this job cannot be ruled out,” Finnish Security Intelligence Service director Antti Pelttari told reporters.

“Who is behind this is a matter for the preliminary investigation. We do not comment on it in more detail,” he added.

Finnish authorities said yesterday that “external marks” had been found on the seabed beside the damaged pipeline and that it was reviewing vessel traffic in the area at the time of the rupture.

A chief investigator also said that it currently looked like the damage was caused by “mechanical force”, not an explosion.

Nato defence ministers are due to discuss the damage today when they gather for a second day of meetings in Brussels. Allies, including the US, have already expressed support for Finland and Estonia.