Flight Centre has been fined $12.5 million for trying to fix the costs of international flights with three airlines for four years.
The company breached the Trade Practices Act five times between 2005 and 2009 by seeking to have Malaysia Airlines, Singapore Airlines and Emirates agree to not undercut their prices.
The airlines sold tickets through their websites at a lower price than available through travel agents, which Flight Centre complained was eating into its profits.
Under the "price beat guarantee" policy, Flight Centre's margins were reduced when trying to compete with direct sales from airlines operators.
The attempt to induce the airlines into price-fixing arrangements resulted in legal action being brought by the Australian Competition and Consumer Commission, which came towards an end after Wednesday's fine was imposed.
In the years in which the price-fixing attempts occurred, Flight Centre's revenue grew from $900 million to $1.7 billion.
Legal costs are still to be determined.
