Organisers of the Soccerex football conference have vowed to take legal action against Brazilian authorities after the six-day event was cancelled due to security concerns.
The conference was expected to unite a slew of football identities, including England coach Roy Hodgson and FIFA president Sepp Blatter at the Maracana stadium from Nov 30 to Dec 5.
Tuesday's decision has renewed concerns over the prospect of disruptions to next year's World Cup, to be held in 12 Brazilian cities from June 12 to July 13, reported Xinhua.
Soccerex cited "ongoing civil unrest" for the decision and promised to seek compensation.
"Preparations for the event at the Maracana stadium were well advanced with content planned, speakers confirmed and partnerships in place," a statement said.
"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."
The state government denied security concerns were to blame, saying the decision was based on funding problems.
Anti-government protests that begun during the Confederations Cup in June have continued in Rio de Janeiro and Sao Paulo in recent weeks.
In July, Blatter warned that nationwide marches that overshadowed the Confederations Cup were "like alarm bells for Brazil's government".
Protestors have cited excessive public spending on the World Cup and Olympics instead of essential services like health, education and transport as key reasons for their discontent.
FIFA's marketing director, Thierry Weil, said Soccerex's cancellation had not caused alarm.
"We do not believe this will have any influence in any way or form on the organisation of the FIFA World Cup," he said.
