Google has said it will let its human reviewers listen to audio recordings made by its virtual assistant only if users give it fresh permission to do so.

Axar.az reports citing BBC.

The company said the option had always been opt-in but it had not been explicit enough that people were involved in transcribing the clips.

The pledge follows Apple's switch to an opt-in model in August.

Amazon and Facebook, by contrast, make users ask if they want to be excluded.

Google's move has been welcomed by digital rights campaigners.

"Companies should do the right thing and make sure people choose to be recorded," Open Rights Group executive director Jim Killock said.

"They shouldn't be forced into checking that every company isn't intruding into their homes and daily conversations."

Google has said about one in 500 of all user audio snippets would be subject to the human checks.