Updated

Brazil has opened legal proceedings against several major international companies accused of fixing prices for the construction and upkeep of public transportation systems in five cities.

Brazil's antitrust agency says in a Thursday statement it will investigate the bidding process for contracts on subway and train systems of Sao Paulo, Brasilia, Belo Horizonte, Porto Alegre and Rio de Janeiro.

The statement says 18 companies were part of a cartel involved in 15 projects valued at $4 billion.

According to the government's official gazette, the companies include Germany's Siemens, CAF of Spain, Mitsui of Japan, Bombardier of Canada and Alstom of France.