Facebook must stop tracking non-users in Europe within 48 hours, a judge in Belgium ruled on Monday.
The decision stems from a complaint by Belgian officials alleging that Facebook sets tracking cookies when people visit pages on Facebook.com, even if those people don't have accounts with the service. Facebook then is able to track those people when they visit sites with a "Like" button.
"Facebook can not follow people on the internet who are not members of Facebook which is very logical because they can not have given permission to follow them," Bart Tommelein, Belgian secretary of state for the protection of privacy, said on Monday in a statement emailed to Reuters.
Facebook could be fined approximately $269,000 per day for failing to comply with Monday's ruling. The company reportedly plans to appeal.
Facebook has argued that its cookie helps prevent security breaches and protect against spam and malware. The company also says that it sheds data about people's Web-browsing after 10 days, according to The Wall Street Journal.
The ruling marks the latest twist in an increasingly heated battle over privacy between U.S.-based Web companies and European authorities. Europe, unlike the U.S., has a broad privacy law that restricts companies from collecting certain types of data without users' permission.
Last month, Europe's highest court invalidated an agreement that previously enabled companies to easily transfer data about Europeans to the United States.
Europe's highest court also created a "right to be forgotten" in May of 2014, when the judges ruled that Google and other search engines must allow residents of European countries to delete search results that link to embarrassing information.
Google interprets that decision to require it to delete results from country-specific search engines, like Google.fr (for Google France) or Google.it (Google Italy), but not from the overall Google.com. But France's data protection regulator told Google in September to broaden the right to be forgotten by censoring search results worldwide.