BEIJING - China's top three airlines reported robust combined profits, even as currency losses from a weakening yuan eroded earnings.

Air China Ltd, China Eastern Airlines Corp and China Southern Airlines Co stepped up sales of yuan-denominated bonds and cut dollar debt to reduce financing costs, as the local currency depreciated the most in more than two decades in the fourth quarter against the greenback.

Net income at all three fell short of estimates, as losses from swings in foreign exchange dragged down total combined profits to16.3billion yuan ($2.4 billion), exchange filings showed on Thursday.