The US internet giant acknowledged "misconduct" in the leak of the Dutch language conversations by one of its language experts contracted to help refine its Google Assistant, the artificial intelligence-powered system for voice interactions.
Google made the announcement Thursday following a report by Belgian broadcaster VRT that it could access fragments of conversations from smart speakers and other Google devices in Belgium and Netherlands.
The leak appeared to be from one of the language experts Google uses around the world to help it refine its program.
"We just learned that one of these language reviewers has violated our data security policies by leaking confidential Dutch audio data," Google product manager David Monsees said in a blog post.
"Our security and privacy response teams have been activated on this issue, are investigating, and we will take action. We are conducting a full review of our safeguards in this space to prevent misconduct like this from happening again."
The incident highlighted concerns about smart speakers and devices "listening" to private conversations or archiving audio files that could be inappropriately accessed.
Privacy activists have accused Amazon of inappropriately storing conversations with children on its Echo Kids devices, asking for a federal investigation.
Amazon has said it complies with federal laws on audio data and relies on guidance from family safety experts for its data storage.