Sydney airport rates last among Australia’s top five.

Competition regulator the ACCC has rated Sydney airport Australia’s worst for overall performance for the fourth year in a row.

In its annual report on the nation’s five biggest airports, the Australian Competition and Consumer Commission said "indications are that Sydney airport has increased profits by permitting service quality to fall below that which the airlines reasonably expect.

"Airport users, including passengers and airlines, rated Sydney airport last among the monitored airports for the fourth consecutive year, and it appears that investment in the international terminal has been slow.

"And while Sydney was the only airport to report a fall in passenger numbers, its revenue and profit margins still increased.

"Sydney recorded the highest average prices at $13.63 per passenger, compared to the lowest at $7.96 at Melbourne airport.

The commission also expressed concern that some airports may have been exploiting their monpoly position with car parking charges.

Brisbane was rated No.1 for overall performance, followed by Adelaide, Perth, Melbourne and Sydney.

A total 93.3 million travellers passed through the five major airports in 2008-9, an increase of just over 1% on the previous 12 months.

Sydney accounted for more than one-third with 32.7m.

Melbourne was second-busiest with 24.8m, followed by Brisbane 19.1m, Perth 9.7m and Adelaide 6.9m.