The Millennium Stadium has cancelled a party for Cardiff's gay and lesbian Mardi Gras and hit out at the city's council for allowing a rival event.
The event is Cardiff's seventh annual Mari Gras festival
The stadium was to host a Saturday night event for up to 40,000 people.
But the council granted a licence for a free street party nearby on the same night, prompting the stadium to say its event was "doomed to failure".
A council spokeswoman said: "Cardiff plays host to a number of events, often more than one event at any one time."
The main event for the seventh annual Cardiff-Wales Lesbian and Gay Mardi Gras festival takes place from 1300 BST in Cooper's Field, near Cardiff Castle.
The Millennium Stadium had organised an evening party for festival-goers afterwards, which was to have seen the stadium roof closed and an acoustic curtain in place to reduce noise to nearby residents.
But Millennium Stadium chief executive Paul Sergeant said the decision by Cardiff Council's highways authority to grant permission for a street closure in Charles Street for a free party, organised by a nightclub, meant that their event would have to be cancelled at short notice.
Acts will still perform at the extended main event
Mr Sergeant said: "We have today taken the decision to cancel our Mardi Gras post-show party as a direct result of Cardiff Council granting an all-singing, all-dancing, free street party in Charles Street on Saturday night.
"Our involvement was on the basis there was both a need and desire to give Mardi Gras revellers somewhere safe to congregate in the evening.
"To accommodate the event, the stadium dedicated a huge amount of resources, turned away other business and spent thousands of pounds.
"Top class bands were lined up (and) considerable advertising was put in place."
Mr Sergeant said they had been working closely with festival organisers and been planning the event for months.
The Millennium Stadium was to hold a party after the main event
Mr Sergeant added: "It has cost us money, badly affected our credibility and left us with a very bitter taste in our mouths.
"We knew all along that if we went head-to-head with a free gig we would be doomed to failure."
Mardi Gras organisers said the street party was organised unofficially by a local club adding they were disappointed with the stadium's decision to cancel.
Rob Keetch, co-chair of Cardiff Mardi Gras, said: "We have extended the main event in Cooper's Field by an hour to 9pm, incorporating many of the acts which were due to perform at the stadium".
Charlotte Church, Gina G and Bjorn Again are among those appearing.
"Venues in Cardiff don't have the capacity for the amount of people who will be in the city for the Mardi Gras, so the Millennium Stadium was perfect," said Mr Keetch.
"We are disappointed in the stadium, but the main Mardi Gras event has not been cancelled."
Reacting to Mr Sergeant's comments, a Cardiff Council spokeswoman said: "Cardiff plays host to a great number of events, often more than one event at any one time.
"All applications whether for licensing or road closures must be considered independently and on their own merits.
"A number of road closures have been granted on the grounds of public safety. The street parties have not been organised by the council."