EU regulators are drawing up a “hit list” of up to 20 large Internet companies, likely to include Silicon Valley giants such as Facebook and Apple, that will be subject to new and far more stringent rules aimed at curbing their market power.

Under the plans, large platforms that find themselves on the list will have to comply with tougher regulation than smaller competitors, according to people familiar with the discussions, including new rules that will force them to share data with rivals and an obligation to be more transparent on how they gather information.

The list will be compiled based on a number of criteria, including market share of revenues and number of users, meaning the likes of Facebook and Google are likely to be included. Those deemed to be so powerful that rivals cannot trade without using their platforms could also be added.