RIYADH - The $23 billion Riyadh Metro launched an auction on Sunday for private companies to name and advertise in select metro stops when the system opens in 2019, an initiative that could generate millions of dollars to help cover operational costs.

Construction on the 176-kilometre (110 miles) metro began in 2014 after contracts were awarded to consortiums headed by U.S. construction giant Bechtel Corp, Spain's Fomento de Construcciones y Contratas and Italy's Ansaldo STS.

The metro's six lines and 85 stations are scheduled to be operational by the end of 2019. They will be served by electric, driverless trains in what officials describe as the world's largest public transport system currently under development.

Construction has pushed ahead amid speculation the project could be scaled back or delayed following a slump in Saudi Arabia's oil revenues. The metro is part of the country's ambitious programme to reform the economy and society.

Local and international companies licensed in the kingdom will be eligible to bid for naming and advertising rights at 10 stations, said officials from the state-run Arriyadh Development Authority (ADA), which oversees the metro project.

Another 10 stations could be offered at a later auction. Bids must be submitted by Jan. 25 and winners will be announced by mid-2018, the officials said.

"(The revenues) will be allocated for running the train and supporting the public transit system in the city", said Alwalid Alekrish, Director of Construction Development Projects and Project Director of the Riyadh Metro.

He declined to specify how much the auction was expected to generate, but the potential is large. The metro in neighbouring Dubai has earned hundreds of millions of dollars with a similar initiative, according to local media.

Promotional materials suggested winning companies would have their logos plastered throughout the stations - at turnstiles, elevators, passageways and shopping areas.

(Reporting by Stephen Kalin, editing by Louise Heavens) ((stephen.kalin@tr.com; +971 52 322 9759; Reuters Messaging: stephen.kalin.thomsonreuters.com@reuters.net))