SAN FRANCISCO • The New York state Attorney-General's Office plans to open an investigation into Facebook's unauthorised collection of more than 1.5 million users' e-mail address books, according to two people briefed on the matter.
The inquiry concerns a practice unearthed this month in which Facebook harvested the e-mail contact lists of a portion of new users who signed up for the network after 2016, according to the two people, who spoke on condition of anonymity because the inquiry had not been officially announced.
Those lists were then used to improve Facebook's ad-targeting algorithms and other friend connections across the network.
The investigation was confirmed late Thursday afternoon by the Attorney-General's Office.
"Facebook has repeatedly demonstrated a lack of respect for consumers' information while at the same time profiting from mining that data," Ms Letitia James, the Attorney-General of New York, said in a statement. "It is time Facebook is held accountable for how it handles consumers' personal information."
Facebook said the unauthorised practice, first reported by Business Insider earlier this month, was "unintentional", a mistake resulting from a method the company once used to verify the identity of new users that required sending Facebook their e-mail passwords.
Though that practice - which security experts said left users vulnerable to identity theft - ended in May 2016, Facebook continued to gain access to the e-mail address books of at least 1.5 million new users.
Users were not notified that their contact lists were being harvested at the time. Facebook shuttered the contact list collection mechanism shortly after the issue was discovered by the press.
Facebook said it was in touch with the Attorney-General's Office and was responding to questions about the issue. The Attorney-General's investigation will focus on how the practice came about, and whether or not the e-mail contact collection spread to hundreds of millions more people across the social network, according to the two people.
Meanwhile, Facebook is suing a company and three individuals based in New Zealand over allegations that they sold fake likes, views and followers to users of its photo-sharing platform Instagram, it said on Thursday.
"By filing the lawsuit, we are sending a message that this kind of fraudulent activity is not tolerated on our services, and we will act to protect the integrity of our platform," Facebook said in a statement.
Users with large numbers of followers are often able to attract lucrative sponsorship deals and sell products on their platform if they are considered to be influencers.