RIO DE JANEIRO -- The track and roof of the velodrome built for last year's Rio de Janeiro Olympics was damaged in a fire Sunday when the building was struck by a small, hand-made hot-air balloon.
A charred area could be seen on the roof of the structure, and shots from TV network Globo showed a 20-30 meter (yard) portion of wood track surface had burned.
The racing surface was made of special Siberian wood, a requirement that made the velodrome one of the last venues to be ready for the Olympics.
The Brazilian sports ministry confirmed the incident with no injuries reported. In a statement it said the damage was being evaluated.
Despite being illegal, the release of the hand-made balloons -- or lanterns -- is common in Brazil. The balloons often cause fires when they land.
The incident took place just a few days short of the one-year anniversary of the Rio Games, which opened on Aug. 5.
The velodrome cost about $45 million and, like a half-dozen other sports arenas in the Olympic Park, is struggling to find a use. Many of the arenas are boarded up, and the park in suburban Barra da Tijuca is largely vacant with few amenities for visitors.
Brazil spent about $13 billion in public and private money to hold last year's Olympics, with some reports suggesting the overall cost is closer to $20 billion.
The costs are a flashpoint because Brazil is going through its deepest recession in a generation.
The state of Rio de Janeiro has been late paying teachers, police and pensions, and the military has been arriving in Rio over the last few days to try to control the city's soaring violence.