Fake coronavirus marshals and phoney medical professionals are pretending to be genuine to get inside people's homes, Brits have been warned.
Today the Chartered Trading Standards Institute (CTSI) said the scam is an updated form of one in the summer involving fake healthcare professionals offering bogus Covid-19 tests on doorsteps.
Covid-secure marshals were announced as part of a Government plan to enforce stricter rules on social gatherings.
They have no formal powers and do not have the right to enter anyone's home.
The Prime Minister said last month that the marshals would "boost the local enforcement capacity", but the Ministry of Housing, Communities and Local Government (MHCLG) said they would not be given enforcement powers in new legislation.
Katherine Hart, CTSI's lead officer for doorstep crime, said: "Since March we have seen so many different instances of fraudsters using the pandemic as an opportunity to defraud the public.
"These scams are shifting in their theme as the rules and regulations change with individuals now pretending to be Covid-19 secure marshals.
"Covid-19 secure marshals will never come to your door unannounced and do not have the right of entry, or the right to issue fines.
"This type of scam appears in many forms, and I have also received information about individuals pretending to offer flu vaccinations on the door, a concerning development as we enter flu season.
"I am particularly concerned that elderly and vulnerable individuals may be at risk to this scam.
"I ask the public and public authorities to spread the correct safeguarding information so that we can stop these unscrupulous individuals from ruining the lives of those already struggling during this challenging time."