Chinese budget carrier Spring Airlines is offering free tickets to Japan to boost demand after a bilateral territorial dispute over islands in the East China Sea led to scores of travelers cancelling or postponing trips.

The country's largest private low-cost carrier is offering free round-trip tickets between Shanghai's Pudong airport and Japan's Saga prefecture, a rural area in southern Japan near the city of Fukuoka, until December 20, airline spokesman Zhang Wuan said.

Spring Airlines' flights to Saga, which run three times a week, are now more than half empty compared with 90 percent occupancy before the islands dispute escalated.

Violent protests and calls for boycotts of Japanese products broke out across China in mid-September after Japan bought two of the East China Sea islands, known as the Diaoyu in Chinese and the Senkaku in Japanese, from their private owners.

The offer of free tickets comes after a Saga official visited Spring Airlines in Shanghai, expressing hope that the route would continue with the local Saga government's support, Zhang said. He declined to comment on what support is being offered.