Users of Amazon's Alexa digital assistant can now request that recordings of their voice commands delete automatically.

Amazon says it saves such commands to improve the service. But the practice has raised concerns with privacy experts who say the recordings could get into the wrong hands, especially as Amazon and other companies use human reviewers rather than just machines.

Previously, users had to go into Alexa's settings and delete recordings manually. Users can now ask Amazon to automatically delete recordings after three months or 18 months. But users need to specify that in the settings, as recordings are kept indefinitely by default. And there's no automatic option for immediate deletion. Users would still need to do that manually.

When users ask for automatic deletion, a warning will pop up saying that doing so could degrade Alexa's ability to respond or understand users.

Amazon will also let users request deletions through an Alexa voice command. The use of human reviewers will continue.