The scheme to install new energy meters in every home in the UK should be halted because of spiralling costs, a consumer campaign group has warned.
Which? said the government, rather than energy companies, should install the "smart meters" to keep costs down.
But Energy Minister Charles Hendry said the £11.1bn cost of introducing them to 30 million homes and firms from 2014 to 2019 would reap an £18.1bn benefit.
The devices show exactly how much gas and electricity is used in real time.
The project has been led by energy companies who have been installing the meters house-by-house as customers ask for them.
Which? claims it would be better if the government co-ordinated the installation process, whole streets at a time.