Another $255 million is needed to complete the extension of Rio de Janeiro's metro line connecting tourist areas to the site of the 2016 Olympics, city officials said Friday.

Rio's transport secretary said that the city was waiting for a late payment this month of about $120 million from the federal budget and that then another $135 million would be needed to finish the project.

"These funds are indispensable for us to finish the work in time for the Olympics, which means in July," the official, Carlos Osorio, was quoted as saying by O Globo newspaper.

The extension will reach Barra de Tijuca, the western area of the sprawling city where much of the Olympics will be held and where the Olympic Village is located. It is considered a vital element in plans to handle the huge number of visitors.

The metro is also being integrated with a new system of express buses running in dedicated lanes to reduce what are often tortuous journey times in a city with complicated geography and major traffic jams.

In July, a government auditor warned that the metro was at "high risk" of not being completed in time for the games, which start August 5.

The funding concerns come as Brazil struggles with a deep recession, a political crisis in which President Dilma Rousseff faces possible impeachment and a huge corruption scandal.

Caught up in that scandal is construction giant Odebrecht, the lead member of the consortium building the metro. Its former CEO, Marcelo Odebrecht, is in detention and resigned his post on Thursday.