Facebook has been paying outside contractors to transcribe audio clips from users of its services, Bloomberg reported on Tuesday, citing people familiar with the matter.
The company confirmed that it had been transcribing users' audio and said it was no longer doing so, Bloomberg reported.
Facebook did not immediately respond to a Reuters request for comment.
Bloomberg, citing the company, reported that the users who were affected chose the option in the Messenger app to have their voice chats transcribed. The contractors were checking whether Facebook's artificial intelligence correctly interpreted the messages.
Shares of Facebook pared gains after the report and were up 1.66 percent at US$188.44.
The social media company has been facing broad criticism from lawmakers and regulators over its privacy practices.
Last week, a federal appeals court rejected Facebook's effort to undo a class action lawsuit claiming that it illegally collected and stored biometric data for millions of users without their consent. The company also agreed to pay a record US$5 billion fine last month to settle a US Federal Trade Commission data privacy probe.
Earlier this month, Apple and Google globally suspended reviewing recordings from users interacting with their voice assistants, as concerns over data privacy mount.
(Reporting by Nivedita Balu and Sayanti Chakraborty in Bengaluru; Editing by Maju Samuel)