ATHENS – Greece’s counter-terrorism squad on Tuesday announced the launch of an investigation into anonymous threats to contaminate food in supermarkets with acid, posted on the Indymedia website on Monday.

The post under the headline “Greek Nemesis Act 3” is signed by the “Greenblack Arsonists” and threatens to sabotage specific products on supermarket shelves in Athens and Thessaloniki by injecting them with hydrochloric acid using a syringe. There are also photographs demonstrating how the foods will be tampered with.

This is the third year that the specific group has threatened to sabotage foodstuffs before Christmas, with similar threats posted last year and in 2013. On both previous occasions, the food products listed in the threat were withdrawn by the companies involved and the threat was shown to be hoax after investigation.

The group claimed that the acid-laced products of the three firms named will be returned to the shelves between Wednesday and Christmas Eve, at different supermarkets in Athens and Thessaloniki.

Police authorities have alerted the Hellenic Food Authority and the three companies named in the Indymedia threat so that they can withdraw their products as a precaution, as well as launching an investigation to find those responsible.