(ECNS) -- A domestic airline company has set more restrictions on the sale of lower-priced tickets on the Internet, National Business Daily reported Tuesday.

Several agents confirmed they had received a notification from Air China requiring them to price tickets at no less than 98 percent of the airlines' website equivalent, or face being fined.

Mandatory bundles are also not allowed, agents revealed. They couldn't bundle tickets with coupons or other products such as insurance in a way that airlines don't recognize, otherwise they will be subject to a fine of 1,000 yuan per flight segment.

Lin Zhijie, a civil aviation researcher, said it's a strategy airlines use to increase the volume of direct sales. He revealed that such sales could save the company a large amount of marketing costs.

Air China's earnings report in the first half showed its market cost was 3.325 billion yuan, 272 million less than last year.

An unnamed insider said direct sales currently accounted for some 27 percent, and that the number was expected to reach 50 percent by 2017.