A report by the AP said that the Finnish military says it has dropped depth charges onto a suspected submarine in the sea outside Helsinki after twice detecting the presence of a foreign object in the area.
The navy's maritime operations chief, Olavi Jantunen, says they could not identify the "underwater object" but had begun an investigation, which could take weeks.
“We strongly suspect that there has been underwater activity that does not belong there. Of course it is always serious if our territorial waters have been violated,” Defense minister Carl Haglund told Finnish news agency STT.
A UPI reports quotes Navy chief of staff Admiral Juha Vauhkonen saying that it’s not yet possible to say whether or not the underwater object detected in waters near Helsinki was a submarine.
"If the object does turn out to be a sub that violated Finnish territorial waters, the matter will be investigated by the Finnish Border Guard," he said.
He did not want to speculate on whether or not there were any similarities with a search for a submarine in the Stockholm archipelago by Swedish officials.
Carl did not say whether Russian involvement was suspected.
Finnish media reported that although the target was believed to have left the area, the investigation into the incident would continue.
Finland has observed an increase in military exercises by Russia, with which it shares an 800-mile border. In October the Finnish military activated troops, helicopters and ships to a search of the Stockholm archipelago for a suspected Russian submarine, which, it was later, learned, was a Swedish civilian boat.