Facebook has said that political data firm Cambridge Analytica improperly harvested the public profile data of up to 87 million of its users, including their political beliefs, interests and friends’ information.

Now the social network has revealed that the extent of the harvesting went even further — it included people’s private messages, too.

On Monday, Facebook began informing people whose data may have been compromised by Cambridge Analytica through an app developed by researcher Alexander Kogan. In its notifications, Facebook said that while the information harvested was largely limited to what was on people’s public profiles, “a small number of people” also shared information from their Facebook timeline, posts and messages.

Facebook did not specify how many people’s messages were gathered and said it was taking as broad a view as possible when notifying people that their data may have been taken.

The revelation widens the scope of data that was harvested from people on Facebook and how it went beyond what was publicly available.

It is not clear whether the direct messages were among the data eventually provided to Cambridge Analytica. In an interview Tuesday, Kogan said the private messages were harvested from “a couple thousand” people who completed his questionnaire, not their friends.