Adverts on websites like Gumtree are proving popular for scammers
People looking for rental accommodation in Oxford are being warned of a money transfer scam being run by conmen posing as landlords on the internet.
Oxfordshire Trading Standards said fraudsters had been advertising properties on free websites.
When a potential tenant makes contact, the conmen ask for a wire transfer and a transaction code as proof of funds.
Trading Standards said it was "virtually impossible" to catch the criminals or reclaim the money.
Tom Swarbrick, 22, of Abingdon, inquired about a flat in Oxford he saw advertised on Gumtree.com.
He said: "The landlord said he was in Cardiff and would only show me round when I could prove I could afford to rent it.
"He wanted two months rent - about £1,100 - transferred to a friend of mine and a receipt as proof, he also wanted the secret transaction code Western Union gives to its customers."
Mr Swarbrick became suspicious and immediately contacted Trading Standards.
A spokesperson for the website Gumtree.com said: "Unfortunately fraud is an industry wide problem that we take very seriously.
"We regret if any of our community members have fallen victim to incidents of fraud, we do our best to protect anybody who uses Gumtree.com, the vast majority of whom have a safe and successful experiment."
Richard Webb, deputy head of Oxfordshire Trading Standards, said he had seen similar scams targeted at students but that fraudsters were using more sophisticated methods to con people out of money.
"It's virtually impossible to catch these people, they're using a free website with no verification of who they are when they place the advert," he said.
"Western Union is notoriously difficult to trace the money through, we don't know where the money will end up, it's likely to go overseas."