Toll road giant Transurban will overhaul its fees amid suggestions it has been reaping millions by slugging motorists with excessive charges.

Documents leaked to Fairfax revealed Transurban, which operates roads in Victoria, NSW and Queensland, hauled in $147 million in 2016 by charging customers fees for pursuing unpaid tolls, image matching and replacing eTags.

The Victorian government said it is trying to make the toll system fairer for motorists under a new agreement for its controversial West Gate Tunnel project.

“As part of the West Gate Tunnel Project, we’ve negotiated a fairer deal for drivers that use CityLink, including a massive overhaul of toll enforcement and infringements,” a government spokesman said in a statement on Tuesday.

“Unfortunately, the Liberals and the Greens have previously indicated that they intend to oppose these measures.”

The Andrews Labor government has negotiated changes to the way Transurban handles unpaid tolls and fines, including doubling the time the company has to contact people over missed tolls and hardship concessions.

However, those changes are dependent on an extension of Transurban’s deed over the CityLink road passing parliament.

Transurban told Fairfax the fees charged to motorists were reflective of the cost, but it would be announcing fee changes next week.

The Greens say secrecy over Transurban’s cash flow needs to end.

“Today’s revelations demonstrate that Transurban is overwhelmingly driven by increasing profits rather than working in the interests of commuters,” federal transport spokeswoman Janet Rice said in a statement.

“What’s worse, with state governments increasingly prioritising toll roads over public transport, Transurban’s profits are going through the roof while people are locked into using these expensive toll roads because they have no other transport option.”

AAP has contacted Transurban for comment.