(ANSA) - Milan, April 26 - An association of food delivery firms on Friday said they were "stunned" by threats aimed by delivery riders on social media against high-profile customers 'outed' for not tipping them.

"We are stunned by the statements published on Facebook by the Deliverance Milano group, above all in relation to the issue of privacy and the threats, thinly disguised, that were aimed at some concumers," said AssoDelivery, which represents Deliveroo, Glovo, Just Eat, Social Food and UberEats.

The riders' collective posted a list of VIPs who were allegedly measly with tips or did not tip at all.

AssoDelivery said it had reported the case "to the competent authorities."