The Hungarian Competition Authority fined Facebook for misleading users into believing its services were free of charge. The $4 million fine, the biggest to date for the tech giant, was issued to Facebook's Ireland subsidiary.

"While users did not have to pay a fee for using the service, they still made a profit for the company through their user activity and data," the competition watchdog said in a statement.

The Menlo Park-based company recently had to pay £500,000 ($657,000) for violating data protection laws in a 2018 data-gathering scandal involving Cambridge Analytica.