Twitter has started tracking users' behaviour outside of app and website in a move it says will let users see more targeted adverts.

The update means the 140-character social network can now collect browsing data on users when they visit websites that have embedded timelines or tweet buttons. It will store this information for 30 days so that it can "further improve and personalise" its adverts.

The changes, which were announced in an update to Twitter's privacy policy, include the creation of a new section that lets users see how the network profiles them based on their activity. It features a list of the interests Twitter and its partners think a user has, what apps they have downloaded, and the companies that are targeting them.