Facebook employees raised concerns about Cambridge Analytica’s data-scraping practices three months earlier than thought, according to US court documents.
A US-based employee warned colleagues about the activity in September 2015.
Facebook had said it previously discovered the improper sharing of data on 87 million people three months later, in December 2015.
The firm said the September concerns related to a separate matter.
The news suggested that Facebook had “consistently misled” Parliament’s Digital, Culture, Media and Sport (DCMS) committee, said the committee Chair Damian Collins MP on Twitter.
Mr Collins has previously criticised its chief executive Mark Zuckerberg for failing to appear before the committee to face questions about the scandal.
According to the court documents, the Facebook employee “warned” the company about Cambridge Analytica’s behaviour and discussed it with colleagues.