The Federal Court has fined Flight Centre for trying to fix prices for international flights with three airlines in a ruling the travel agency says it may challenge.

Flight Centre has been ordered to pay $11 million for trying to prevent Singapore Airlines, Emirates and Malaysia Airlines from offering cheaper flights than its own airfares between 2005 and 2009.

Flight Centre says it complies with the law and changed its business practices after the Australian Competition and Consumer Commission (ACCC) launched an investigation into the price fixing attempts in 2009.

ACCC chairman Rod Sims says the penalty would have been higher if Flight Centre had successfully convinced the airlines to fix their prices.

"Flight Centre was found to have made the attempt, the airlines didn't agree so because it was an attempt it therefore gets a lower penalty than otherwise and so we think the penalty is a reasonable one," he said.

In December, the Federal Court found Flight Centre had tried six times to prevent the airlines from undercutting its prices on international flights.

It ruled the travel agency had tried to "induce an anti-competitive arrangement" to maintain its margins.

The court found senior management were involved in the breaches, with chief executive Graham Turner having direct and personal involvement in one of them.

Justice John Logan said emails sent by Mr Turner in 2009 were evidence of "the most blatant of all the charged attempts to induce".

Flight Centre has already appealed against that judgement and says it is now considering also challenging the penalty.

Mr Sims defended the amount of time it took to mount the case and says it sets an important example.

"These processes do take time," he said.

"I don't think that matters because the key point is this helps define the law, it helps send signals to companies about what they can and can't do and that's why it's hugely important."