Members of a French bird protection group were attacked by a man in his underwear wielding a shovel after they discovered finch traps on a plot of land in southern France.

In a series of images, a man dressed in a t-shirt and underpants can be seen attacking members of the LPO (Ligue pour la Protection des Oiseaux, or “Bird Protection League”), including the group’s president Allain Bougrain-Dubourg.

The incident happened on Monday as the activists investigated a farm in Audon, south-western France. They were accompanied by journalists to highlight a number of illegal finch traps on the property, according to the organisation.

They dismantled a number of the traps and were then set upon and “physically assaulted” by two men; the man in his underwear and a second wielding a hoe.

“Vehicle tires were slashed but it was not the worst,” a statement on the LPO website said. “Four LPO activists including the president, the vice president and the secretary general were violently attacked.”

The LPO members were treated in hospital for bruising and later filed a complaint with the police, according to the statement.

The incident has since gone viral and been labelled “Slipgate” - from the French word “slip”, meaning “underpants”.

The story drew attention on social media, with a number of parodies and photoshopped images of the attacker appearing.

Finch trapping is illegal in France and is punishable by a one-year prison sentence and a €15,000 fine, according to the LPO.

Poachers set traps at this time of year, tracking the migration pattern of the birds. The birds are then killed and eaten, according to the LPO website.