Londonderry Radio 1 Big Weekend tickets appear online
Radio 1 says it will work to stop the secondary sale of tickets for its Big Weekend in Londonderry.
Some of the tickets have appeared on auction websites, such as eBay.
Radio 1 says it "reserves the right to cancel" any tickets sold on by people who got passes to the event in Derry.
The 37,500 tickets were snapped up in under an hour for the event, which will take place at Ebrington over the spring bank holiday weekend in May.
The full line-up has yet to be released, but Olly Murs and Two Door Cinema Club have been confirmed so far.
In a statement, a spokesperson for Radio 1 said: "Tickets for BBC Radio 1's Big Weekend Derry~Londonderry are free and we work with those running major auction websites and sales outlets to have posts offering tickets for sale or trade removed.
"Those offering tickets for sale are breaking the Terms & Conditions they agreed to during the booking process and we reserve the right to cancel them."
The issue is also addressed in the Frequently Asked Questions section on the Radio 1 Big Weekend website.
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