Staff at the Co-op are being ordered to keep their cameras on during remote work meetings, and verify all attendees, as the company deals with an ongoing cyber attack.
In an internal email to the 70,000 members of staff at the supermarket, funeral service and insurance company, workers are being urged to be vigilant as IT teams work to ensure hackers aren't inside their systems.
"Don't record or transcribe Teams calls", the instructions say.
It disclosed on Wednesday that it had shut down parts of its IT systems in response to hackers attempting to gain access.
It comes as supermarket Marks & Spencer (M&S) has pulled all job adverts from its website, as it struggles with a major cyber attack.