RIO DE JANEIRO (Reuters) - Brazilian prosecutors said on Thursday they were investigating the process by which companies were selected to complete work on the Rio de Janeiro Olympic velodrome and equestrian venues.

State prosecutors in Rio de Janeiro said in an emailed statement the probe was sparked by press reports that private construction companies Zadar and Engetecnica were contracted without a public bidding process.

Zadar and Engetecnica could not immediately be reached for comment. Rio's city government said in a statement it lacked time for a public bidding process.

"The city could not stop the works to comply with time requirements," the statement said. It said Zadar and Engetecnica were hired under emergency contracts.

Zadar and Engetecnica were hired by Rio's city government to finish construction after the original builders were dismissed for failing to deliver the work on time.

Federal prosecutors and police are investigating a multitude of Olympic projects and legacy infrastructure works for suspected corruption.

Most of the building for the Olympics, which will run Aug. 5-21, has been carried out by construction firms ensnared in Brazil's biggest corruption scandal, a kickback scheme at state-run oil company Petrobras [PETR4.SA].

Newspaper Folha de S.Paulo reported last week that the two companies belong to Paulo Roberto Moraes, the father of the leader in the state legislature of the Brazilian Democratic Movement Party. Mayor Eduardo Paes is a member of the same party.

(Reporting by Stephen Eisenhammer; Editing by Richard Chang and Grant McCool)