A flaw in Google's miniature voice-activated speaker meant some of the devices constantly recorded owners without them knowing.

The Home Mini smart speaker is designed to respond to commands when it hears the wake phrase "OK Google". But a flaw in the new speakers meant a few early-release devices would listen to and record their owners constantly.

The flaw could confirm one of consumers' biggest fears about smart speakers: that they can be used to eavesdrop on private conversations. Google said the problem was accidental and that it has now been fixed.

Artem Russakovskii, reporter at Android Police, spotted the flaw in the £49 Home Mini that Google had given him to review. The fault in the Mini, which affected an unspecified "small number" of the devices, meant the speaker would listen to every sound, regardless of the wake phrase.

"The Mini was behaving very differently from all the other Homes and Echos in my home - it was waking up thousands of times a day, recording, then sending those recordings to Google," said Russakovskii. "All of this was done quietly, with only the four lights on the unit I wasn't looking at flashing on and then off."