Facebook's operations chief said the world's largest social network needed to earn back public trust and was investing billions of dollars a year to improve the security of its network.

Chief Operating Officer Sheryl Sandberg also said on the sidelines of the World Economic Forum in Davos that the group's founder, Mark Zuckerberg, should remain its chief executive and chairman.

Facebook had a tough 2018 as it was buffeted by revelations that UK consultancy Cambridge Analytica had improperly acquired data on millions of its US users to target election advertising.