The Itaquerao stadium, due to host the opening match of the 2014 World Cup, was 94% completed at the time of the accident.
The damage could delay the completion of the stadium, which must meet FIFA's December deadline.
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The Commons Public Accounts Committee (PAC) said at least £9 million has been squandered on a project that failed to deliver.
A top temperature of 11 Celsius (52 F).
The event, which was held at the Dorchester Hotel last Thursday, was attended by representatives of some of Britain’s biggest companies.