Qantas has agreed to help the ongoing investigations

The carrier will also pay a $61m (�27.4m) fine, the US Department of Justice said in a statement.

It said Qantas was part of a conspiracy to fix the cost of shipping cargo from at least January 2000 to February 2006.

US authorities fined British Airways �300m in August for trying to fix the price of fuel surcharges.

'Aggressively pursue'

"Qantas' guilty plea sends a clear message that those who engage in price fixing and other forms of illegal collusion will pay a heavy price for their crimes," said Department of Justice Assistant Attorney General, Thomas Barnett.

Qantas has also agreed to co-operate with the department's ongoing investigation into air cargo prices.

Back in August, Korean Air Lines was also fined over the cost of air cargo shipments.

"Our investigation into this important industry will continue, and we will aggressively pursue those who engage in criminal conduct that harms American consumers," added Mr Barnett.