Soccerex claimed in a statement that the Rio de Janeiro state secretary of sport took the political decision to withdraw support from the Soccerex Global Convention, which was to be held at the Maracanã Stadium in the Brazilian city in a matter of weeks, due to "ongoing civil unrest".
However the state government denied this was the reason, saying Soccorex had failed to raise sufficient funds. It said in a statement: "The state guarantees the security of multiple events, including New Year's Eve on Copacabana beach, carnival, and the World Cup.
"The government of Rio de Janeiro encouraged the organisers to seek cultural and sports incentives [funding] and they failed to do so. Soccerex were advised to seek funding to host the event so that the state would not have to use public money."
Brazil is hosting the World Cup next year.
The convention was due to be held between 30 November and 5 December, with a two-day festival preceding the three-day conference for more than 4,500 delegates, including the England manager Roy Hodgson.
Soccorex said preparations were well advanced. It added in a statement: "To be summarily cancelled in such a cavalier fashion, having hosted 33 events over five continents is extremely frustrating but nevertheless it has happened and is in contravention of all of the contractual obligations of the Rio State Government, who have been notified of our intention to instigate legal proceedings for substantial compensation."
Duncan Revie, Soccerex CEO, said: "On behalf of all at Soccerex, I would like to apologise to every business, football club, league, federation and media organisation affected by this news.
"This unique and cruel conclusion to our time in Rio was completely out of our hands and everyone who has attended a Soccerex event over the last 18 years will know this is not how we do business. We must look forward now to 2014, to our new event calendar and the Global Convention in Manchester".
The Soccerex Global Convention is to be held in Manchester for the next four years beginning in September 2014. Soccerex said the Soccerex African Forum will take place in Durban, South Africa, in November and two other Soccerex events, one in Russia, and one in the Americas will be announced soon.