Finnish authorities said Friday they had traced a cyber attack against the country's parliament last year to a hacker group associated with the Chinese government.

The Finnish parliament announced in December that it had been the target of a cyber espionage operation.

The attack - which speaker of the house Anu Vehvilainen dubbed "a serious threat against our democracy and Finnish society" - had been carried out at an unspecified date "during the autumn."

Finland's security service SUPO traced the attack to an actor which US security firm FireEye has designated APT31, believed to be acting at the behest of China's government.

"We are quite sure of the conclusion, but unfortunately we can't comment on the methodology," a spokeswoman for SUPO told AFP in an email.

SUPO also couldn't comment on what sort of information may have been compromised, as the matter was still the subject of an investigation.

"We can state that the operation targeted the very heart of Finnish decision-making and is considered a very serious matter," the spokeswoman said.

According to FireEye, APT31 focuses on "obtaining information that can provide the Chinese government and state-owned enterprises with political, economic, and military advantages."