Damage to an underwater natural gas pipeline with Estonia on Sunday may have been deliberate and was probably caused by “external activity”.

After a sudden drop in pressure, the Baltic-connector pipeline was shut down. The cable of a telecom company was also damaged.

Finland’s prime minister announced on Tuesday that the leak’s source had been found and was under investigation by both countries.

As of yet, Petteri Orpo hasn’t been able to determine the cause of the incident.

It is believed that Russian sabotage is retribution for Finland joining NATO in April this year, according to Finnish sources.

According to Norsar, the Norwegian seismological institute, there was a “probable explosion” along the Baltic Sea coast of Finland at 01:20 on Sunday (22:20GMT on Saturday). As measured at 1.0, the explosion was much smaller than the one that targeted the Nord Stream pipelines in September 2022.

According to Finland’s National Bureau of Investigation (KRP), there were “no indications” that explosives were used, although the damage was so severe it would take months to repair.

Cable and pipeline damage occurred at two different locations in Finland’s Exclusive Economic Zone, authorities said.

The damage discovered could not have been caused by normal pipeline use or pressure fluctuations, Mr Orpo said at a press conference. There had already been an exclusion of other possible causes, such as seismic activity.

Finland is the only country with direct access to the gas network of the wider European Union through this pipeline. Even so, Orpo said the country’s energy security was not at risk since it had enough alternative sources of gas.

The NATO military alliance’s head, Jens Stoltenberg, recently wrote on X (formerly Twitter) that the alliance “shares information and stands ready to support allies concerned”.

European gas prices have risen because of the possibility that the damage was deliberately done.