By Fiona Pryor
Entertainment reporter, BBC News
The BBC is launching a stage at the festival this year
Glastonbury Festival organisers are taking action against customers who are selling tickets on eBay.
People are being tracked via details submitted when registering for tickets and asked to withdraw their auction.
"If people try and come there's a very high likelihood that they will be spotted," said Melvin Benn, the operations manager for the festival.
For the first time this year, festival goers had to submit a photograph in a bid to stamp out ticket touts.
Festival founder Michael Eavis has admitted he was "disappointed" by the quality of a small number of the photo tickets issued.
In April after the first batch of tickets had gone on sale, Eavis was assured the registration system had been a "success" as no-one had listed any to sell on eBay.
But they have started to appear on the auction website with auctioneers suggesting bidders only attempt to buy if they bear a strong resemblance to them.
Mr Benn said they have managed to contact most of the people who are attempting to sell tickets on eBay.
"We're telling them that the tickets are cancelled. One of the conditions we had were that they weren't for resale and that we have got the right to cancel them."
But a ticket will only be cancelled if festival-goers attempt to gain entry to the event with a ticket which fails to match their identity.
"We will be very vigilant about it and intend to stop people coming who are not identified on the ticket," added Mr Benn.
Some people who have been contacted by Glastonbury claim they have been subject to threatening phone calls.
Mr Eavis thought the new system had beaten the ticket touts
"I was told they had my details and if I didn't remove the listing immediately Glastonbury were going to prosecute me for fraud," said a 26-year-old student from Hull.
He was trying to sell the ticket because his grandmother's funeral coincided with the opening of the festival.
His ticket only gave him access if he travelled via coach on the first day of the event.
"In a way I feel very let down. You think of Glastonbury as having a liberal ethos, but instead I feel like I have been hit by a corporate machine," he added.
When the BBC News website told Mr Eavis his story, he agreed to allow him access to the event at any point during the weekend as long as a death certificate was provided.
A 50-year-old man from Cheltenham is also trying to sell his ticket after losing his job soon after making the purchase.
About 400,000 people pre-registered to buy tickets
His new job will not agree to give him the time off.
"They said 'we demand that you withdraw the ticket from eBay otherwise we'll take legal action,'" he said.
"If they refund my money then I would take it off eBay, but they won't do that," he added.
Mr Benn admits they have insisted tickets be removed from the auction site, but denies threatening legal action.
"I don't believe it is a fraudulent act, but it's an act that breaks a condition of sale," he "Certainly not to my knowledge has anyone been suggesting that it's fraud," he said.
Mr Benn added if anyone had a valid reason to be unable to attend the festival then his team would "certainly look at every one".