BRUSSELS (BLOOMBERG) - Facebook must stop tracking Belgian users' surfing outside the social network and delete data it's already gathered, or it will face fines of €250,000 (S$400,000) a day, a Belgian court ruled.
Facebook "doesn't sufficiently inform" clients about the data it gathers on their broader web use, nor does it explain what it does with the information or say how long it stores it, the Brussels Court of First Instance said in a statement.
The social network is coming under increasing fire in Europe, with a high-profile German antitrust probe examining whether it unfairly compels users to sign up to restrictive privacy terms.
Belgium's data-protection regulators have targeted the company since at least 2015 when a court ordered it to stop storing non-users' personal data.
While the US tech giant won an earlier appeal in 2016, Friday's ruling is the first in a European court to go to the heart of the company's use of technology deemed to be essential to its proper functioning.
"Facebook can follow your surfing behaviour without you realising it, let alone want it, on the basis of those invisible pixels that Facebook has placed on more than 10,000 other websites," the court said.
The company is "disappointed with today's verdict" and intends to appeal, Facebook's head of public policy for Europe, Richard Allan, said.
"The cookies and pixels we use are industry standard technologies," Allan said.
"We require any business that uses our technologies to provide clear notice to end-users, and we give people the right to opt-out of having data collected on sites and apps off Facebook being used for ads."
Facebook must publish the 84-page ruling on its website and display extracts in Belgian newspapers within three months, a court spokeswoman said.
It also rejected Facebook's arguments that a Belgian court couldn't rule on a business headquartered in the US and which runs operations for the rest of the world from its Irish unit.
The court said it was competent to rule on breaches of Belgian privacy law when the company tracks web users in Belgium.