Facebook has been fined almost £9m by Italian authorities for misleading users about how it used their data.

Italy’s competition watchdog handed the social media giant two fines totalling €10m (£8.9m), the first for “misleadingly” encouraging people to sign up “without informing them in an immediate and adequate way” of how their data would be sold to third parties.

The second fine was for “aggressively” discouraging users from trying to limit how the company shared their personal information, by telling them that doing so risked them experiencing “significant limitations”.

The fine dwarfs the £500,000 fine imposed on the social network by the British Information Commissioner’s Office earlier this year for breaking data laws.

Italy’s AGCM consumer and market watchdog also said in a statement that Facebook does not make clear to users that the social network makes money from data, “simply stressing the fact that it’s free”.

It ordered Facebook to publish a “corrective statement” to all users on the desktop site and mobile apps.

The data at the centre of the ruling was harvested from a personality quiz app downloaded by hundreds of thousands of people in Italy. As permitted by Facebook’s rules at the time, the app gathered details about users’ Facebook friends without their knowledge.

The data was then allegedly used by British firm Cambridge Analytica, which filed for bankruptcy earlier this year, and is now facing damages claims totalling more than £40bn from Facebook users whose personal information was allegedly misused by the firm.

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Professor David Carroll told the High Court in London he was suing the company for up to £20,000 in damages under the Data Protection Act, over what his solicitor described as "Cambridge Analytica's misuse of his data".

Prof Carroll's solicitor, Ravi Naik of ITN Solicitors, said in a witness statement he represented "numerous others" bringing similar claims against the company.

Prof Carroll "has a claim of between £5,000 and £20,000 in respect of Cambridge Analytica's misuse of his data", Mr Naik said, and referred to Facebook's estimate that Cambridge Analytica had harvested up to 87 million users' data.

How to stop Facebook from revealing everything about you Show all 9 1 /9 How to stop Facebook from revealing everything about you How to stop Facebook from revealing everything about you Lock your profile down If you haven’t done this already, do it now. In Settings, hit the Privacy tab. From here, you can control who gets to see your future posts and friends list. Choose from Public, Friends, Only Me and Custom in the dropdown menu. How to stop Facebook from revealing everything about you Limit old posts Annoyingly, changing this has no effect on who’s able to see your past Facebook posts. Instead, on the Privacy page, you have to click on Limit Past Posts, then select Limit Old Posts and finally hit Confirm on the pop-up. How to stop Facebook from revealing everything about you Make yourself harder to find You can stop completely random people from adding you by selecting Friends of Friends from the dropdown menu in the Who can send you friend requests? section of the Privacy page. It’s also worth limiting who can find your Facebook profile with your number and email address. At the bottom of the page is the option to prevent search engines outside of Facebook from linking to your profile. How to stop Facebook from revealing everything about you Control access to your Timeline You can limit who gets to post things on your Timeline and who gets to see posts on your Timeline too. In Settings, go to Timeline and Tagging and edit the sections you want to lock down. How to stop Facebook from revealing everything about you Block people When you block someone, they won’t be able to see things you post on your Timeline, tag you, invite you to events or groups, start conversations with you or add you as a friend. To do it, go to Settings and Blocking. Annoyingly, you have to block people on Messenger separately. You can also add friends to your Restricted list here, which means they’ll still be friends with you but will only be able to see your public posts and things you share on a mutual friend's Timeline. How to stop Facebook from revealing everything about you Review tags One of Facebook’s handiest privacy features is the ability to review posts you’re tagged in before they appear on your Timeline. They’ll still be visible on the News Feed while they’re fresh, but won’t be tied to your profile forever. In Timeline and Tagging, enable Timeline review controls. How to stop Facebook from revealing everything about you Clean up your apps You can view a list of all of the apps you’ve connected to your Facebook account by going to Settings and Apps. The list might be longer than you expected it to be. It’s worth tidying this up to ensure things you no longer use lose access to your personal information. If you don’t want to log into websites and apps with your facebook account, scroll down and turn Platform off. How to stop Facebook from revealing everything about you Change your ad preferences You can view a list of everything Facebook thinks you’re into and tinker with your ad preferences by going to Settings and Adverts. A lot more information is displayed on the desktop site than the app, so we’d recommend doing this on a computer. How to stop Facebook from revealing everything about you Download your data Facebook lets you download all of the data it has on you, including the posts you’ve shared, your messages and photos, ads you’ve clicked on and even the IP addresses that are logged when you log in or out of the site. It’s a hell of a lot of information, which you should download to ensure you never over-share on the social network again.

"Even if one conservatively uses the lowest end of the range, both in number and value of each claim, and calculates on the basis of 10 per cent of the estimated 87 million affected Facebook users only, with claims of £5,000 each against Cambridge Analytica, that still implies a total potential claim value of £43.5bn," he said.

Of the Italian fine, a Facebook spokesperson said: “We are reviewing the authority’s decision and hope to work with them to resolve their concerns.