Earlier in the day, energy operator Gasgrid Finland said that the pipeline between Finland and Estonia had been shut down on Sunday night after an unusual drop in pressure, which could have been caused by a leak.
"The Border Guard will investigate this incident on its own, to the extent possible at sea," the head of the communication unit of the Finnish Border Guard, Kimmo Ahvonen, was quoted as saying by Finnish broadcaster YLE.
The Finnish Security Intelligence Service (Supo) will also be involved in the investigation, the broadcaster said it was told by a spokesperson.
Finland's Central Criminal Police has yet to comment on its participation, although YLE believes that it will be this agency to lead the investigation.
Meanwhile, Estonia's Elering energy company said it did not rule out that the pipeline could have been damaged deliberately.
"A deliberate rupture of the gas pipeline cannot be ruled out. I would not like to speculate on this issue, but this is more likely to be external damage," Elering chief spokesman Ain Koster told Estonian broadcaster ERR.
The suspension of the pipeline will not in any way affect the gas supply to Estonian consumers as, following the incident, gas is being supplied to Estonia from Latvia, where the Incukalns underground gas storage facility is located, ERR said. At present, professionals from both countries are trying to identify the exact location of the leak, it added.
Senior Vice President of state-owned transmission system operator Gasgrid Finland, Janne Gronlund, said on Sunday that the resumption of Balticconnector would take months.
Balticconnector is a 25-mile gas pipeline which lies at the bottom of the Gulf of Finland between the southern Finish municipality of Inkoo and Estonia's Paldiski. Both countries have compressor stations and onshore gas transportation routes that connect the gas pipeline to their respective transport networks. It is located in the economic zones and territorial waters of both Finland and Estonia. The pipeline was commissioned in December 2019.