The warning comes after Wolverhampton City Council's trading standards service received reports of a man tricking his way into the home of an 82 year old resident in the Willenhall area.
The man showed a false ID card which bore a photograph and the words "Trading Standards" on it and claimed to be carrying out investigations in the area.
He left on foot shortly afterwards and it is not clear whether or not anything was stolen.
Wolverhampton trading standards have today issued advice for potentially vulnerable residents to help them avoid being tricked.
Paul Dosanjh, Wolverhampton City Council's Trading Standards section leader, said: "We are very concerned to hear of people posing as council officials.
"Offenders often target elderly or vulnerable residents in order to gain access to their homes to carry out crimes such as distraction burglaries.
"Our officers would not turn up without making a prior appointment and they would provide their full names and a contact number for people to check to ensure they are who they say they are.
"We would urge all residents to be on their guard and report any suspicious callers to either West Midlands Police or us."
People can report any such suspicious behaviour to the Citizens Advice Consumer Service on 0845 404 0506.
West Midlands Police also advice householders in the Black Country to use the 'Stop, Chain, Check method if someone who looks official knocks on the door.
Stop and think if you have invited them, have the chain on the door whilst talking to them and check their identification carefully.
- released: Tuesday 6 May, 2014