HNA Tourism Group, a unit of HNA Group, said on Monday that it was buying a 24.1 percent stake in Nasdaq-listed online tourism firm Tuniu Corp for $500 million, as consolidation moves gathered pace in China's tourism sector.

Yan Haifeng, chief operating officer of Tuniu, said the transaction is expected to close next month, adding that it would use the $500 million for developing resources at its tourism destinations.

The transaction is a milestone for the company as it comes close on the heels of a staggering 433.7 million yuan ($67.85 million) net loss in the third quarter of 2015, despite a 127.5 percent rise in net revenue during the same period.