Hainan Airlines, the fourth-largest airline in China, reported a net profit of 1.93 billion yuan ($310 million) in 2012, down 26.74 percent year-on-year, the carrier said in its annual report released on Thursday.

The carrier's revenue was 28.87 billion yuan in 2012, up 9.87 percent year-on-year, due to the increase of its fleet, it said.

Higher human resources and agency services costs led to a 46.55 percent year-on year rise of the carrier's expenses.

The air passenger and freight transport of Hainan Airlines was 4.2 billion ton-km in 2012, up 7.56 percent year-on-year, and its average load factor was 84.44 percent.

Stiffer competition in China's civil aviation industry, the slow growth of the cargo market and the development of the high-speed rail network all had a negative effect on China's airlines last year.