French and German users of the Meta platform have also been targeted, according to researchers from the non-profit groups AI Forensics and CheckFirst. In May, they estimated that 275,000 sponsored posts containing anti-Ukrainian and anti-EU messages had reached over three million Facebook users in Poland, France, Italy and Germany.

Amaury Lesplingart of CheckFirst said: “The rash of illegal ads violating platform rules is a wake-up call for both Meta and regulators to enforce existing regulations more closely.”

Hundreds of fake accounts have been uncovered by researchers, and it was via these profiles that ads were bought. Five ads declared “There is no place for Ukraine in the EU”. Another, directed at Polish users, announced: “We are all accustomed to constant reports of thefts in Ukraine, but sometimes we are surprised by the cynicism of Ukrainian thieves.”

Of the ads directly related to political and social issues, over 65% were not flagged as such in EU countries; of these, Meta removed less than 5%.

As things stand, buyers of political ads on Meta are obliged to show official identification and are banned from promoting their message outside their country of residence.

Meta, however, have refuted the findings and queried how researchers’ defined political adverts. The findings are now being investigated by the European Commission.