Amazon on Wednesday added the ability to tell its Alexa digital assistant to forget what it has heard in a move that could assuage concerns about Echo devices remembering conversations.

The command "Alexa, delete everything I said today" will get the virtual aide to do just that, the internet colossus said in an online post.

Amazon added it was working on narrowing the command to ordering Alexa to delete what was just said.

Alexa is the brains in voice-controlled Echo smart speakers, which feature microphones.

Concerns have been raised that internet-linked smart speakers with built-in microphones or cameras could snoop on private conversations or moments.

The new feature will be added to an Alexa privacy hub that provides controls for information shared with or by Echo devices, which also allow microphones and cameras to be turned off.

Microphones and cameras on Echo smart speakers can also be turned off.