A Russian government aircraft is suspected of violating Finnish airspace on Wednesday morning, according to the Finnish Ministry of Defence.
The suspected airspace violation, involving an Mi-17 helicopter, took place along Finland's eastern border between the towns of Kesälahti and Parikkala at around 10:40 on Wednesday morning, according to the ministry.
The Mi-17 is a Soviet-designed Russian military helicopter.
The aircraft flew a distance of 4-4.5km into Finnish territory, the ministry added.
Finland's Border Guard has opened a preliminary investigation into the incident.
"This is the second airspace violation committed by a Russian aircraft this year," the ministry's communications chief, Kristian Vakkuri,said.
The previous airspace breach took place on 8 April and involved a Russian state-owned passenger jet.
The defence ministry only publicly announces airspace violations by state, not civilian, aircraft.
About 20km apart, the towns of Kesälahti and Parikkala are both about 10km west of Finland's border with Russia.
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