HELSINKI/MOSCOW (Reuters) - Finland’s defense ministry said on Tuesday it suspected a Russian aircraft had violated Finnish airspace over the Baltic Sea earlier in the day.

The ministry said a Tupolev TU-154, a Russian passenger and transport plane, had been detected south of Porvoo and that the border guard was investigating the matter.

A ministry spokesman declined to say whether Finland had scrambled jets to identify the plane. The Russian defense ministry was not immediately available to comment.

Finland, which is preparing to celebrate 100 years of independence on Wednesday, has accused Moscow of several airspace violations since the Ukraine crisis began in 2014.

Last year, Estonia and Finland blamed Russia for entering their airspace as Finland was signing a defense pact with the United States. In a separate incident, two Russian warplanes flew simulated attack passes near a U.S. guided missile destroyer in the Baltic Sea.

Finland was part of the Russian Empire and won independence during the 1917 Russian revolution, then nearly lost it fighting the Soviet Union in World War Two. It is now an EU member state which does not belong to NATO military alliance.