Hundreds of music fans have been turned away from a festival after finding their tickets were fakes.
Live Nation, promoters of this weekend's Barclaycard Wireless Festival, said many of those who had purchased tickets from third party websites such as Gumtree and eBay have been refused entry as their tickets are counterfeit.
The three-day event at London's Hyde Park has seen 65,000 revellers enjoy performances by acts including Nicki Minaj and Professor Green, while Rihanna headlines tonight.
Ms Dynamite performs at the Barclaycard Wireless Festival
Live Nation said the fraudulent tickets had been created by parties preying on music fans who did not use approved and official ticket outlets.
A spokesman said: "This is outrageous and has to stop, we urge fans to only use the official ticket outlets at all times."
Those who bought fake tickets are advised to contact the National Fraud Intelligence Bureau through their website www.nfib.police.uk.