Google's voice-activated assistant is coming to Nest's security camera, in a move that could arise privacy concerns.

The virtual assistant is being offered to owners of the Nest Cam IQ in a free update rolling out Wednesday.

Google's assistant already can be used to control Nest's cameras and internet-connected thermostat through its internet-connected speaker, Home, and smartphones running on its Android software.

The assistant is activated with keywords such as "OK, Google," although there have been instances when the Home speaker has been caught listening when it was supposed to be turned off.

Privacy watchdogs are worried that Google eventually may use some of the information collected from devices inside homes to get a better understanding of a person's specific interests so it can sell ads for products that the targeted individual might like -- a tactic already widely followed by Google in search engine and other free services.