Residents in Bury St Edmunds have been warned following reports of 'Nottingham Knockers' attending properties in the west Suffolk town.
The salesmen, who were reportedly in Bury on Wednesday, claimed to have been in prison and on a youth offending scheme, Suffolk Trading Standards said.
They would try and sell the homeowners a range of everyday household products at high prices.
One resident reported that they paid £80 in cash to a man who showed a HMP lanyard to them, while another said they were approached at the door by a man from Liverpool claiming to be out of prison.
Suffolk Trading Standards said the men may have moved on to somewhere else in the county.
So-called 'Nottingham Knockers' work in groups across the country but they are not involved in any officially recognised offender rehabilitation programme.
Many do not possess Pedlar’s Certificates, which are issued by police.
Anyone approached at the doorstep by someone claiming to be out of prison is urged to refuse to purchase anything.
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