Air China Ltd , the country's flag carrier, said its third-quarter net profit rose 61.7 percent to 3.77 billion yuan (US$556.02 million) over the same period last year, helped by strong summer travel demand.

Revenue over the quarter, traditionally the peak travel season for the Chinese airlines, rose 2.22 percent year-on-year to 31.9 billion yuan from 31.3 billion yuan, against a 9.2 percent rise in passenger traffic, the airline said on Thursday.

"Benefiting from a relatively strong summer holiday, domestic passenger demand grew steadily and the outbound tourism stayed robust. However, the cargo business continued to be sluggish," the company said in an e-mailed statement.

This contributed to a 15.1 percent rise in January-September net profit to 7.23 billion yuan from a year earlier, it said.

The company said operating costs rose 5.81 percent as international oil prices rose slightly, though they remained low. Airlines are seeing previous cost savings from low fuel prices evaporate as oil prices, which plunged in mid-2014, regain ground.

A robust travel season also eased the impact of the weakening yuan, which has in recent months caused heavy foreign exchange losses for Air China and its rivals who have been aggressively expanding their fleets using large-scale U.S. dollar borrowing.

Passenger capacity, measured by available seat kilometres, rose 7.63 percent, while the passenger load factor edged up by 1.18 percentage points to 82.92 percent, Air China said.

The company said fluctuating exchange rates and geo-political risks posed challenges to the industry, though the overall market and supply demand trend looked to be positive.

Air China's Hong Kong-listed shares closed down 0.58 percent on Thursday ahead of the results, against a 0.83 percent dro in the Hang Seng Index.

Meanwhile, rival China Eastern Airlines Corp Ltd , the country's second-largest carrier, said its net profit for the first nine months of the year rose 25.5 percent.