Ticket selling companies StubHub and Viagogo have been raided as part of an investigation into touting.
Competition and Markets Authority officials seized data which could reveal industrial-scale touting which has ripped off millions of concert goers.
Investigators are hoping to shed light on both companies and their relationships with ticket touts, who keep back tickets for popular artists including Drake and Adele and sell them outside venues.
The Guardian reported the raids are part of an investigation launched last year about ticketing companies not giving fans enough information about who is selling tickets on the sites.
The CMA is believed to have issued an ‘information notice’ to Stubhub, Viagogo, GetMeIn and Seatwave.
StubHub’s office on Tottenham Court Road in London and Viagogo’s office on Cannon Street were raided in August.
Both Parliament and National Trading Standards have concerns about the ticket selling market in the UK.
A National Trading Standards spokesman said: ‘We are concerned that consumers are being left out of pocket after using secondary ticketing websites to purchase tickets.
‘With concerts and events increasingly refusing to accept resold tickets we’d strongly advise people take steps to protect themselves by only buying tickets from official sellers, most of which are working with the authorities to help ensure more tickets are made available to genuine fans through official vendors.’
A spokesman for StubHub said: ‘We understand the CMA investigation is ongoing and therefore await the outcome of this.’
Metro.co.uk has contacted StubHub and Viagogo for a comment concerning the raids.