Stuart Galbraith, former managing director of Live Nation, has warned against the company's proposed merger with Ticketmaster.
The deal, which has been referred to the Competition Commission in the UK, would bring together the world's biggest ticket retailer and concert promoter.
Speaking to BBC 6 Music, Galbraith said the potential monopoly would have a “detrimental effect”.
"I don't think it would be a good thing,” he added. “I think competition is good for the customer and good for everybody that participates in live music."
The reported $575million agreement between Ticketmaster and Live Nation was first mooted in February.
A host of musicians, including Seal and Shakira, have already endorsed the proposed merger.
But there are concerns in the US and the UK over whether it would harm other ticket sellers.
Galbraith, who is currently running Sonisphere festival, said: "I can hardly see how you get two companies which both have a history of charging high booking fees then going, 'Great, let's bring booking fees down'.
"I think you'll actually see the opposite and booking fees go up.”
Both Live Nation and Ticketmaster have already been asked to justify the move to the US Subcommittee on Antitrust, Competition Policy and Consumer Rights.
Meanwhile, the Competition Commission is expected to rule on the proposed deal by November 24.