Bangkok governor Chadchart Sittipunt is planning to collect fares along two Sukhumvit Line extensions.
Mr Chadchart on Thursday held a meeting with Krungthep Thanakom, City Hall's business unit, and his advisory team on the Green Line, which is operated by Bangkok Mass Transit System Plc (BTSC).
Mr Chadchart said the details of the Skytrain system must be reviewed as it involves many agencies.
The Green Line extension's concession will not be renewed under the Public-Private Partnership Act, and the outstanding debt owed to a private operator worth about 40 billion baht must be reviewed, Mr Chadchart said.
Regarding debt, Krungthep Thanakom reported that some revenues from the railway line extensions from the On Nut-Bearing and Taksin-Bang Wa sections went to a private firm.
However, the city may have incurred debt from a free ride programme along the Mo Chit-Khu Khot and Bearing-Samut Prakan routes, it said.
To ease the debt issue, fare collection along these two routes may have to start soon, Mr Chadchart said.
"Currently, many commuters in Bangkok must bear the debt of others riding for free along the sections," Mr Chadchart said. "So the debt issue cannot be used to expedite the concession renewal process because the private firm also benefits from the free rides."