A section of the roof of the Arena Fonte Nova in the northeastern city of Salvador was not able to sustain the large amount of water that settled on top of it after it rained heavily overnight. There were no injuries.
Workers tried to remove water from the roof to keep other parts from collapsing. Television images from local channel Record showed about 20 people using buckets to clear the sections of the roof which still had water on it.
Part of the canvas covering the stands was seen hanging and there was some damage to the seats below. It was one of the 36 panels on the roof that was partially torn apart.
Stadium officials denied any structural problems in the project and said the collapse happened because of a mistake by a worker inspecting the roof on Sunday. They said part of the tarp on the roof was not folded properly, leading to the accumulation of water in that section.
"Repair work has already started and will be concluded in time for the Confederations Cup," Fonte Nova Participacoes said in a statement. "It's an isolated incident. This situation would have never happened during an event because the arena is thoroughly inspected ahead of time."
Local organizers said engineers were sent to the venue to find out what happened.
"FIFA and LOC have been informed that repair work is already underway," the local World Cup organizing committee said in a statement.
The collapse happened the same day Brazilian President Dilma Rousseff praised the country's preparations for the Confederations Cup, the World Cup warm-up tournament.
"I'm certain that Brazil will shine on and off the field," Rousseff said on Monday in her weekly radio program. "I travelled across the country to inaugurate the six Confederations Cup stadiums ... and was impressed with the beauty and the modernity of these new football stages."
The Fonte Nova was inaugurated in April and will host three Confederations Cup matches, including the high-profile matchup between Brazil and Italy on June 22. The first match at the venue will be on June 20, when Nigeria faces Uruguay.
The 56,000 capacity stadium, which will also host the third-place match on June 30, will also be used in the 2014 World Cup, when it will host six matches, including one of the quarterfinals.
In March, heavy rains forced the cancellation of a FIFA inspection visit to the Maracana stadium, which was under renovation for the Confederations Cup. Workers there also used buckets to remove water which accumulated in parts of the stadium's recently installed roof.
Local organizers recently blamed heavy rains for the delay in delivering the stadium in Brasilia, which will host the opener of the warm-up tournament on June 15. They said the pitch installation schedule had to be altered because of the rains.
Earlier this year FIFA stressed that it would not accept such excuses for stadium delays ahead of the World Cup.
"It is exactly because of natural challenges faced in big construction works — like the heavy rains observed in Brasília — that the stadiums must be ready enough time before" the tournaments, FIFA and the local organizing committee said. "Delays like the ones observed will not be tolerated for the stadiums that will host only FIFA World Cup matches, which involves a significantly higher number of host cities, teams, fans, matches, journalists and TV audience."
Only two of the six Confederations Cup venues were ready by the December deadline originally established by FIFA. The Estadio Nacional in Brasilia hosted only one test event fully open to the public, and that will also be the case at the Maracana.
FIFA usually wants three test events in each venue, but had to make exceptions in Brazil because of the series of delays.
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