The notice to all House staff said that the “Office of Cybersecurity has deemed WhatsApp a high-risk to users due to the lack of transparency in how it protects user data, absence of stored data encryption, and potential security risks involved with its use.”

The memo, from the chief administrative officer, recommended use of other messaging apps, including Microsoft Corp’s Teams platform, Amazon.com’s Wickr, Signal, Apple’s iMessage, and Facetime.

Meta, which owns WhatsApp, did not immediately respond to a Reuters request for comment.