Webshops displaying a ticking clock to suggest consumers will miss out on an offer when time runs out are misleading and risk being fined in future, consumer watchdog ACM has warned.

The  regulator looked at hundreds of webshops and found 41 to be in breach of the rules, showing countdown timers to suggest a “special offer” would expire after a certain time. In practice the offer would still stand, or a new timer appear to urge purchase at a cheaper price, the ACM found.

What the webshops are doing is illegal, ACM director Edwin van Houten said. “Webshops can tempt but not mislead.”

The timers are part of what the ACM calls “dark patterns”, or ways of influencing buyers to act in ways that are not always to their advantage. Other tactics include pre-filled options or boxes.