Brazil's Minister of Sport Leonardo Picciani has confirmed a fire has damaged the Rio 2016 Olympic Velodrome.
Picciani claimed the incident had been caused by a balloon striking the building and tweeted a picture of further balloons falling near the site.
"The Ministry of Sport deeply regrets the incident this morning at the Velodrome Park and at the same time criticises this criminal practice of releasing balloons," he said on Facebook.
"The Velodrome, a legacy of the Brazilian Olympic Games, was used by athletes and the community of Rio de Janeiro.
"We await and rely on the punishment of those involved for destroying more than a public good, a common site for all.
"After the fire brigade, we will assess the damage and measures to be taken to recover this important national asset."
Velodrome in Rio on fire. Legacy... pic.twitter.com/K4tNl3lPAW— Jamil Chade (@JamilChade) July 30, 2017
During the Rio 2016 Paralympic Games, a small unmanned hot-air balloon crashed into the roof of Carioca Arena 3.
It caused a minor fire and water damage, with Rio 2016 communications director Mario Andrada stating it was most likely launched from one of Rio de Janeiro's favelas.
Balloons are a tradition in the city and are often used to celebrate church feast days.
Photos have shown extensive damage to a section of the track.
Located on the Barra Olympic Park, the velodrome is one Rio 2016 venue where concerns have been expressed over its legacy.
The facility re-opened in May for the first time since the Games and hosted a three-day festival.
This included the Rio de Janeiro State Championship, BMX freestyle presentations and a business exposition.
Organisers hoped the event would promote the velodrome as a major training facility in the region.
It is believed to have cost $44.8 million (£34 million/€38 million) to build.
Delays in its construction meant that no test event was held prior to the Olympic and Paralympic competition.