Warning over conmen posing as Green Deal assessors
Criminals are using the cover of the government's flagship energy policy to defraud money from homeowners.
The Green Deal offers loans to spend on energy-saving home improvement work with no upfront costs.
But trading standards officers have reported that cold callers are posing as Green Deal assessors while charging "administration fees".
Energy Minister Greg Barker told BBC Radio 4's You & Yours that this was simple criminality.
Green Deal loans are only available through government contracted assessors who are identifiable through an allocated number.
Complaints about fraudulent callers have so far been registered with trading standards officers in South Wales and West Yorkshire, where 12 complaints are being investigated.
One 76-year-old said she had been offered an "old age pensioner discount" for double glazing - with a 20% discount if she signed up that day.
Tim Keohane, senior trading standards officer in Caerphilly, said they were dealing with more than 20 complaints across south-east Wales.
"People are handing over up to £400 and not seeing anything again," he said.
"The sort of thing being said is that the Green Deal is absolutely free to householders and that they'll get £10,000 of work for nothing."
Door-to-door sales are permitted under Green Deal legislation.
In February, when asked if this was a safe method of promoting the scheme, Energy Minister Greg Barker said there were strict guidelines and a cooling-off period, but people "at the bottom of society" were unlikely to respond to the internet and newspapers.
Mr Barker has now told the BBC that potential victims are being protected by the rules.
"We have very strong consumer protection, these are fraudsters and if we catch them we will come down on them like a tonne of bricks," he said.
"It would be terrible if we allowed these fraudsters to hijack the Green Deal and prevent it being offered to those at the bottom of the heap in society."
He added the situation would be monitored closely but his inclination was to continue with the policy of contacting people in poor-quality accommodation directly.
Consumers are advised to look out for the Green Deal Approved quality mark which proves assessors and installers are government registered.
The Energy Saving Advice Service can also confirm valid assessors on 0300 1231234.