The Minns government says the cost of a major metro line project linking the city's south west to the inner west is set to exceed the previously announced budget. 

The City and Southwest Metro project, which will convert the T3 Bankstown line to a metro and create a new line under the harbour, was estimated to cost around $12 billion in a 2016 business case. The former Coalition government had publicly announced the project cost to be $18.5 billion in the 2022-23 budget.

Internal government documents allegedly reveal that the former government had actually budgeted for $20.5 billion. 

Transport Minister Jo Haylen has expressed concern that the previously hidden price tag may still not cover the full cost of a fully functioning metro, and the final touches could add an additional billion dollars.

“We are being up-front and honest about the challenges we are inheriting,” she said. 

“Every day, we are asking more about the Sydney Metro and discovering more key details the former government did not reveal to the public.”

The Sydney Metro West line, which will link the CBD with Parramatta, is also facing a significant cost blowout, with internal documents revealing that the budget may now exceed $25 billion, compared to the initially estimated $18 billion. 

Ms Haylen has suggested that this project may be delayed as the administration comes to terms with the budget situation.

Labor had warned during the election campaign that it would adopt a more cautious approach to spending on infrastructure projects, and as such, two further Metro sections have been put on hold, one linking Bankstown to Glenfield and the other linking Parramatta to the new airport line.