Travellers are being slugged higher airfares to cover the fees charged by Sydney Airport and the nation’s three other largest airports for parking and use of infrastructure, the competition watchdog says.

The Australian Competition and Consumer Commission’s annual report card on the airports reveals Sydney Airport’s “aeronautical revenue” rose by more than 4 per cent to $18.30 per passenger last financial year, Fairfax Media reports on Thursday.

ACCC chairman Rod Sims says passengers are paying higher ticket prices as a direct result of a rise in profits per passenger at each of the country’s four largest airports.

“It is not surprising that the airports are so profitable, given that they face little competitive pressure and no price regulation,” he said.

“Airfares are going down but they would have been going down further if you hadn’t had constant increases in the aeronautical charges from the airports.”

The ACCC also continues to raise concerns about the lack of regulation to constrain the market power of Sydney, Melbourne, Brisbane and Perth airports.

“Unconstrained monopolies often have an incentive and ability to charge excessive prices while lacking strong incentives to improve services,” he said.

“They are free to set their prices, and of course, they are monopolies.”