The European Commission said that around 40% of the online shopping websites it monitored were found to be manipulating consumers.
The commission analyzed 399 websites and found that 148 of them contained at least one manipulative tool including fake countdown timers, web interfaces designed to lead consumers to purchases, subscriptions or other choices, and hidden information.
These tools are also called "dark patterns," the commission said.
European Commissioner for Justice Didier Reynders called on national authorities to prevent these practices by strengthening their capacities.
According to the analysis, 42 websites used fake countdown timers, 54 websites directed consumers towards certain choices and 70 websites were found to be hiding important information or making it less visible, AA reports.