An unfinished Brazilian World Cup stadium was damaged more than previously thought by an October fire and may not be ready on time, this according to a report published by Reuters on Saturday.

According to officials in charge of constructing the new Arena Pantanal, the fire wasn't a major cause for concern. However, these new findings throw doubt as to whether the stadium will be finished.

The 18-page report was compiled in December by the Mato Grosso state Public Ministry and stated that there was "structural damage" that "could compromise the overall stability of the construction."

It is hoped the presentation of the document to the Extraordinary Secretariat for the World Cup will encourage local officials to be more cooperative and transparent in future discussions. The contents of the report had not previously been exposed to the public but Reuters have since gained access to the document.

From quotes taken from Reuters, the Public ministry still maintain that the blaze was minor and that no structural damage took place. "It has been impossible to get good information to this point," Clovis de Almeida, a prosecutor at the Public Ministry, told Reuters. "We will make sure that no games occur (at the stadium) until the safety is completely guaranteed."

The fire, which Police say could have been started by an arsonist, reportedly occurred at ground level of one of the main grandstands, which can hold up to 10,000 supporters. The report also contains photos of damage to the stadium, including cracks in concrete pillars, key to the overall core structure of the stand. Other images show "complete decomposition" of concrete on the ceilings above where the blaze took place and some damage to the stadiums steel frame.

"It is emphasized that the loss of resistance of these elements could compromise the overall stability of the construction," said the report.

The deadline for FIFA World Cup stadiums passed in December and the world body has warned unfinished stadiums could be excluded from the tournament. On Saturday, the World Cup stadium in the southern Brazilian city of Porto Alegre held its first test event Saturday, an important step before it's finally handed over to FIFA for soccer's showcase event.

Brazilian club Internacional opened the Beira-Rio in a match against Caxias in a regional tournament, allowing 10,000 of its fans to attend. The stadium will hold 50,000 people, but authorities will not authorize the sale of all tickets until the work is fully finished.

The Beira-Rio is one of the five stadiums yet to be finalized just four months before the World Cup, although work is advanced in and outside the venue.

Information from The Associated Press contributed to this report.