Ewelina Włodarczyk, an analyst at NASK’s Disinformation Analysis Centre, told the Polish Press Agency (PAP) that there were relatively few false claims about the incident.
Most of them, she said, appeared designed to undermine Polish-Ukrainian ties.
One narrative falsely portrayed Ukraine as using Polish territory, with Warsaw’s consent, to attack Russia.
Another claimed Poles were being treated worse than Lithuanians because Ukraine had apologised to Vilnius but not to Warsaw.
NASK also recorded a few isolated posts suggesting Lithuania was preparing action against Poland, including false statements that Vilnius had accused Warsaw of carrying out an attack.
Others claimed the incident was evidence that NATO members, not just Ukraine, were targeting Russia.
The posts appeared on X, TikTok and Facebook.
Poland’s defence ministry told PAP it "firmly denied" reports that the drone had been launched from Lithuanian territory, and urged people not to spread false speculation.
It said the aircraft was Ukrainian and that Kyiv had apologised to Vilnius.
The drone exploded over northern Lithuania on Sunday, and fragments damaged a civilian car.
The driver was not hurt.
Lithuania issued a red alert for two northern regions, and neighbouring Latvia put out a yellow one for three.
Both lasted about 30 minutes.
Lithuanian Defence Minister Robertas Kaunas said the drone was a Ukrainian FPV-1 that had strayed off course during an attack on St Petersburg.
After a meeting of the National Security Commission on Monday, Prime Minister Mindaugas Sinkevičius said there was "no doubt" it had flown in from Poland.
He noted that Lithuanian equipment had recorded the moment it crossed the border.
Vilnius also rejected some Polish media reports that the drone had been launched from Lithuania.
It said its territory had not been, and would not be, used by third countries for military operations against its neighbours.
Polish Defence Minister Władysław Kosiniak-Kamysz said on Monday that several scenarios were being examined, including that the drone was used for smuggling, but confirmed the latest information pointed to Ukrainian aircraft.
He has ordered the military to analyse radar data from the night of 17-18 October, working with Lithuania.
Ukraine’s foreign ministry spokesman, Heorhii Tykhyi, apologised for any disruption and anxiety caused and said Kyiv would share all relevant information with Vilnius.
(ał)
Source: PAP