A Swedish ship is suspected of violating Finnish territorial waters west of the autonomous Åland Islands, the Ministry of Defence said on Sunday.
The suspected violation occurred around 9 pm on Saturday.
The Border Guard is investigating the case.
Niina Hyrsky, Director of Communications at the Ministry, told the Finnish News Agency STT that a Swedish Border Guard patrol ship is suspected of the violation.
According to a preliminary report, the ship crossed some 200 meters into Finnish waters and remained there for about 20 minutes.
Hyrsky said she had no information on how the case came to light, nor any other details.
The Border Guard is to carry out a more detailed investigation of the case.
"They will be able to provide more detailed information when the investigation is over," Hyrsky said.
The Finnish Ministry for Foreign Affairs said on Twitter on Sunday that it had been in contact with the Swedish Embassy in Helsinki and asked for an investigation into the suspected violation of territorial waters.
German warship suspected of violation in 2020
Airspace violations have been more frequent in recent years than those at sea. ¨
In November, a Swedish rescue helicopter breached Finnish airspace near the west-coast city of Vaasa. Last July, Two Russian fighter jets entered Finnish airspace near Porvoo in southern Finland.
"Territorial water violations do happen to some extent," Hyrsky said.
Last year, a German warship was suspected of violating Finnish territorial waters. The incident occurred in January in the Bay of Bothnia off Raahe.
The Border Guard said at the time that the ship was suspected of two violations. At most, the vessel was about 650 meters inside Finnish territorial waters.
