Internet auction site eBay should do more to tackle fraudsters targeting the site, a consumer magazine has said.
eBay is by far the world leader in online auctions
Computing Which? called on the site to be more active in identifying its fraudulent users.
It also wants the site to warn users about the danger of fraud and to crack down on the selling of medical accessories such as contact lenses.
But the site's UK community manager said eBay already had a "safety centre" to help protect its users.
Computing Which? said the link to eBay's Safety Centre had to be made more visible. It said more than 130 incidents were reported to the Metropolitan Police each month.
The magazine's editor, Jessica Ross, told BBC News a recent case saw a gang steal nearly £200,000 from unwitting eBay users.
"It was a six-man gang, they sent e-mails claiming to be from eBay, and tricked eBay users into revealing their passwords and account details.
"The gang then assumed the identity of those legitimate eBay vendors with reliable sales histories, and were able to offer non-existing goods such as Rolexes and laptop computers for sale, only to disappear with the money," she said.
The auction site says its users are often to blame for security breaches
"Many people see eBay as a bit of fun, like Friends Reunited, and no one's denying that it's quick and easy to use. But there's plenty of opportunity for criminals to cash in too."
The magazine said using the site's online money transfer system, Paypal, was safest because it did not involve divulging bank account details.
But eBay said the majority of the fraudulent cases did not take place on the site.
A statement said: "We have been led to believe that, in most of the cases, the users were contacted via e-mail - rather than on the eBay site.
"Payments were made using money transfer services such as Western Union, which are banned on eBay because they are not traceable."