Poland was targeted by a hacking attack from a Russia-linked group this week, the state-run National Research Institute (NASK) said on Wednesday.
The announcement followed accusations by a number of NATO member states that Russia is launching cyberattacks on them, and the Polish foreign ministry has said Poland has previously been targeted.
"Malware targeting Polish government institutions was distributed this week by the APT28 group, associated with Russia's intelligence services," NASK said in a statement.
"Technical indicators and similarities to past attacks allowed the identification of the APT28 group ... This group is associated with the Main Intelligence Directorate of the General Staff of the Armed Forces of the Russian Federation (GRU)."
NASK recommended that network administrators verify whether employees were under attack.
The Russian embassy in Warsaw did not immediately respond to an emailed request for comment, and there was no immediate comment by Moscow.
In response to allegations by Germany that Russia had launched cyberattacks on its defence and aerospace firms and ruling party, Moscow accused Berlin earlier on Wednesday of using baseless myths about Russian hackers to escalate tensions.
