The NSW government says it’s yet to make a decision on whether to introduce a toll in both directions on the Sydney Harbour Bridge and linking tunnel.
The proposal, detailed in leaked documents prepared by the Berejiklian cabinet, would help pay for the $14 billion cost of the proposed Western Harbour Tunnel and Beaches Link.
Motorists travelling north on the bridge would be slugged with a $3 toll for the first time from 2022 as part of the plan, while the full one-way trip on the 14km road linking the northern beaches to the city's inner west would cost about $8.
A similar charge of $3 each way would also apply on the Sydney Harbour Tunnel.
Roads Minister Melinda Pavey's office did not rule out an increase on the Harbour Bridge toll on Wednesday, saying the government was still investigating funding options for the proposed new tunnels.
"As the premier said when she announced the project, we have commenced a market sounding process to investigate funding options and delivery approaches," a spokesman said in a statement.
"That work is not yet complete. We expect to have a detailed plan by the middle of next year."
At present, drivers using the Harbour Bridge or Harbour Tunnel only pay tolls on southbound journeys and the charge depends on the time of the day.
Opposition Leader Luke Foley has warned the government motorists won't be happy about the potential toll increases.
"It seems the Liberals are content to consign motorists in this city to a future where tolls are just levied at an extortionate rate and average income earners won't be able to afford that," he told reporters in Sydney.
The Labor leader believes tolls should be included "in the overall roads mix" for Sydney.
"But they have to be affordable and there has to be an element of public participation when it comes to levying tolls," Mr Foley said.
The confidential cabinet documents, seen by Fairfax Media and the ABC, have also revealed the construction of the new tunnels could cost almost the same amount as Australia's largest road project, the $16.8 billion WestConnex motorway.
The leaked documents represent the second breach of cabinet secrecy in a month.