SYDNEY (Reuters) -Australia's competition regulator sued Qantas Airways on Thursday, accusing it of selling tickets to thousands of flights after they were cancelled, putting the airline at risk of huge fines and reputational turbulence. The Australian Competition and Consumer Commission (ACCC) said in a court filing that the carrier broke consumer law when it sold tickets to more than 8,000 flights between May and July 2022 without disclosing they had been cancelled. The airline kept selling tickets for an average of 16 days after it had cancelled flights for reasons often within its control, such as "network optimisation", the ACCC added.