The official budget for the Rio 2016 Olympics has risen by 70 million reais to 38.67 billion reais ($11 billion), Brazil's Olympic Public Authority (APO) said on Friday.

The increase owes to additional costs associated with Olympic venues, which are now estimated at 6.67 billion reais, APO said in its third so-called matrix of responsibilities report. APO is a federal government organ charged with coordinating spending for the Rio 2016 Games.

The final budget has yet to be approved due to uncertainty about the number of projects needed.

According to APO president Marcelo Pedroso, the figure has fallen to 46 from 56 when the second matrix was published.

"There hasn't been a decrease," Pedroso said. "What has happened is that we have made an improvement. The matrix is a dynamic instrument. It includes a group of projects of the same nature - electric energy - that we decided to join together. We did the same for complimentary facilities."

Apart from the matrix of responsibilities, an extra 7.4 billion reais have been added to the organizing committee budget and 24.6 billion reais to legacy projects.

Meanwhile, APO said 96% of the city's Olympic projects were either underway or completed.

Of the 46 projects that comprise the matrix of responsibilities, 44 have been put to tender while 11 have been concluded.

"The unfinished projects only require a short implementation period," the report said.

Construction work at Barra Olympic Park, the Games' largest venue cluster, is 87% complete, APO added.