"There is a possibility unknown actors have been able to obtain information through the hacking, either for the benefit of a foreign state or to harm Finland," said crime commissioner Tero Muurman.
ADVERTISEMENTEmail accounts belonging to Finnish MPs were compromised during a cyberattack on the country's parliament in the autumn, it's emerged.
Police say they are investigating the "suspected gross hacking and espionage" but have not revealed details of what information was lost.
"The act is not accidental," said crime commissioner Tero Muurman, revealing the incident in a statement on December 28.
"At this stage, there is a possibility that unknown actors have been able to obtain information through the hacking, either for the benefit of a foreign state or to harm Finland."
"The burglary has affected more than one person, but unfortunately we cannot tell the exact number without jeopardising the ongoing preliminary investigation."
While Finland has seen a number of service attacks on state bodies in recent years, closing down websites for several hours, Muurman said this breach was of particular concern.
"This case is exceptional in Finland, serious due to the quality of the target and unfortunate for the victims," he said.
Finland's parliament said it was cooperating with the investigation into the attack, which was detected during "internal technical controls".
“The cyber strike on parliament is a serious attack on our democracy and on Finnish society,” Anu Vehvilainen, speaker of Finland's parliament, said in a statement.
"We must make every effort to ensure a high level of security in both the public and private sectors."
"In order to strengthen cybersecurity, we need our own national actions as well as active action at EU level and other international cooperation."