Artists have been urged to take a stand against “extortionate” dynamic pricing for concerts after Oasis tickets were hiked up to more than double their original price. Fans of the Manchester band expressed their shock and anger after queueing online for hours only to find that the price of the £135 standing tickets had risen to £355. The MP Lucy Powell, the leader of the House of Commons, said she had paid “more than I was expecting to pay” and that she did not like the so-called dynamic pricing model, whereby ticketing sites can raise prices based on demand. Powell said she was “not sure how totally transparent” the process was after hundreds of thousands of fans waited for tickets based on the prices released last week. Fans only discovered at the point of purchase, after spending hours in an online queue, that standing tickets described as “in demand” – costing £337.50 plus fees – were available. These offer the same as the basic £135 tickets despite being more than double the price. Ticketmaster, which is owned by the US entertainment giant Live Nation, defended its dynamic pricing model – similar to that used by hotels and airlines – and said it did not set any ticket prices. The firm has argued that the system is designed to discourage ticket touts by setting prices closer to market value. It says the “in demand” fees are agreed in advance with artists and their management. The Lib Dem culture spokesperson, Jamie Stone MP, said: “It is scandalous to see our country’s biggest cultural moments being turned into obscene cash cows by greedy promoters and ticketing websites. The Oasis ticket fiasco must be a watershed moment and lead to an official investigation, either by the watchdog or a parliamentary body.” Labour has pledged in its manifesto to tackle ticket touting – where secondary sites sell tickets at vastly inflated prices – and is due to launch a consultation on it in the autumn. In Ireland, fans trying to buy tickets for Oasis’s Croke Park gigs for €86.50 (£73) were faced with prices of €415.50 for the same ticket. Regina Doherty, an MEP for the Dublin constituency, called for an investigation into the pricing which, she said, was not “transparent advertising and certainly not fair to consumers”. She added: “Every ticket for these gigs was always going to be ‘in demand’, so slapping an extra label and €300 on some standing tickets is just extortionate.” The European Commission, the executive arm of the European Union, said last year that it was “aware of the concerns” about ticketing websites using dynamic pricing and was “monitoring the situation”. The commission said the “imposition of excessive prices by a dominant company” would be in breach of EU law. Earlier this year, the US Department of Justice announced that it was suing Live Nation for “monopolisation and other unlawful conduct that thwarts competition in markets across the live entertainment industry”. Jonathan Brown, the chief executive of the Society of Ticket Agents and Retailers, defended the dynamic pricing policy and stressed that prices were set by artists. He said people were “used to” the shift in price, comparing it to booking a hotel or travel. But John Robb, the musician and author, said it was “exploiting people’s excitement in the worst possible way … We need the government to look into this, and we need to stop people getting fleeced.” Sean Adams, who manages artists including Charlotte Church and the Anchoress and founded the music website Drowned in Sound, called for MPs to investigate dynamic pricing, but said that “change really needs to come from artists”. He added: “Why does a ‘band of the people’ go along with these corporate dynamic ticket policies that feel like it rips off fans who had the same chance of joining a digital queue as everyone else?” Dozens of Oasis fans complained that they had not been warned that prices might rise when they reached the front of the queue. Prof Michael Waterson, who was commissioned by the previous government to review anti-touting measures in 2016, said it was particularly important for ticketing firms to be transparent about prices in advance. “You can then think about whether you’re willing to pay higher amounts of money and it’s less of a surprise,” he said. UK consumer regulations state that companies must be transparent about the prices they charge and must not mislead customers, such as by providing false or deceptive information or by leaving out important information or providing it too late. The Competition and Markets Authority said it could not comment on individual cases. The ticketing and security expert Reg Walker, who works with major music venues, said Ticketmaster would ultimately emerge as a major beneficiary from the higher fees. “The reason they push it [dynamic pricing] is that if you sell a ticket at £100, at 10% service charge you get £10. If you sell it at £400, you’re getting £40. “So it’s in Ticketmaster’s interests to push this model. I’m not convinced that artists know what they’re getting into.” The Guardian has approached Ticketmaster and representatives of Oasis for comment.