Construction on the already delayed stadium hosting the World Cup opener could be halted because of health and safety concerns for workers.
Prosecutors said Thursday they found irregularities where workers are installing nearly 20,000 temporary seats for the Brazil-Croatia game in four weeks at Itaquerao Stadium in Sao Paulo.
They said the builders were advised about the safety problems a few weeks ago but nothing was done by the time inspectors returned to Itaquerao on Thursday.
The company in charge of the temporary seats, Fast Engenharia, denied it had been notified of the problems, and dismissed the possibility that work would be stopped. It said the prosecutors' complaints were about minor issues, and all of the alleged problems would be resolved by the end of the day.
"If nothing is done we can order a work stoppage," said Roberto Pinheiro Pinto, a member of the public prosecutor's office.
Prosecutors acknowledged the problems were minor. They will send a report to the labour ministry, which would then decide whether to halt construction. Labor ministry officials told local media that although there were some irregularities, it was unlikely construction would be halted.
Labour officials stopped construction at Itaquerao this year after a worker died while installing the temporary seats. Late last year, two workers died after a crane collapsed while hoisting a huge roofing structure.
The builders acknowledge the stadium's roof will not be fully finished for the World Cup, but add that will have no impact on fans and the games.
Thursday's threat comes three days before the local World Cup organizing committee holds an official test event at the stadium. Fast Engenharia said all temporary seats are expected to be ready and tested only next week, so they will not be used in the test event.
As prosecutors made their inspection Thursday, hundreds of people protested near the stadium as part of a wave of demonstrations across Brazil to draw attention to housing and education needs. Dozens of riot police blocked the main entrance next to a construction zone, where cranes and other machines were lined up to carry materials still needed to finish the arena.
Itaquerao is one of the three World Cup venues yet to be completed. The Arena da Baixada in the southern city of Curitiba had its first official test Wednesday, and the other was Arena Pantanal in the western city of Cuiaba. FIFA said recently it was also worried about the delays with the installation of temporary structures at Beira-Rio Stadium in the southern city of Porto Alegre.