The elections watchdog has denied shutting down a Brexit pop festival after organisers accused it of "killing off" the event.
BpopLive struggled to secure performers and tickets were slashed from £23 to £5 as thousands of seats remained unsold.
But Leave.EU blamed the demise of the "Last Night of the Brexit Proms" on the Electoral Commission, accusing it of waging a "spiteful vendetta".
Sister Sledge, East 17, 90's boyband 5ive, Britain's Got Talent judge Alesha Dixon and drum'n'bass act Sigma were among the acts who had pulled out of the festival after finding out it was a political rally.
Elvis impersonator Gordon Hendricks and Cheryl Baker, Jay Aston and Mike Nolan, who made up three quarters of Bucks Fizz but can no longer use the name, were set to play the gig at the 15,000 seater Genting Arena in Birmingham on Sunday.
Leave.Eu's Andy Wigmore, a co-ordinator of the event, said: "This promised to be a truly unique event, with a live orchestra, a little tongue-in-cheek entertainment and speeches from Nigel Farage and other leading lights of the Leave campaign.
"It was intended as a huge and well-deserved "thank you" to all of our supporters; a celebration of their extraordinary efforts in this referendum.
"But the Electoral Commission, which has been pursuing a spiteful vendetta against us since we reported their crooked activities during the Leave campaign designation process to the Treasury Select Committee, has decided to shut us down."
Mr Wigmore said "after insisting we tick all sorts of superfluous boxes and fill in various time-wasting forms in triplicate" the elections watchdog issued a "final demand for more information".
"Despite our best efforts, the constant pressure and repeated threats have finally killed off what should have been a great event for our dedicated and hard-working supporters," he added.
The Electoral Commission said it had "outstanding queries" about the event but had not called for it to be cancelled.
A spokesman said: "The commission has not requested or suggested that the event cannot or should not take place. As part of the commission's monitoring we identified an event that had it proceeded would need to comply with the rules on referendum campaign spending.
"As we would in any such matter, we contacted the event organisers regarding the costs and administration of the event and have been awaiting a response to outstanding queries on this. It is important that the campaign spending rules are followed properly."
Leave.EU campaign chief Arron Banks said 8,000 ticket holders would be offered a refund or allowed to attend the postponed concert in September, which will be staged in aid of his Love Saves the Day foundation.
Mr Banks made a string of allegations about the Electoral Commission, including claiming it had a "long record of general incompetence".
"After June 23rd we will be taking aggressive action to ensure the wider public comes to share that opinion. They are not fit for purpose, utterly incompetent and have overseen the transformation of the Britain's electoral process into a circus worthy of a corrupt banana republic."