Euromonitor said the growth in the household incomes of people on the Chinese mainland would lead to a higher appetite for travel.

Outbound departures were defined in the report, called “megatrends shaping the future of travel”, as foreign trips that last more than 24 hours.

Bob McKercher, a professor at the school of hotel and tourism management at Hong Kong Polytechnic University, said part of the reason China will top the table is that Hong Kong and Macau are counted as international travel.

“There is still a frontier between mainland China, Hong Kong, and Macau, because when Hong Kong and Macau returned to Chinese rule, the World Trade Organisation retained their separate frontiers from mainland China,” McKercher said in an interview.

Between January and September, 46.68 million foreign tourists visited Hong Kong, of which 78 per cent, or 36.63 million, were from the mainland. That represented growth of 12.7 per cent among Chinese visitors, versus just 0.8 per cent growth for visitors from elsewhere.

Transport projects such as the Guangzhou-Shenzhen-Hong Kong Express Rail Link, and the Hong Kong-Zhuhai-Macau Bridge were expected to further boost travel between the mainland and the two Special Administrative Regions.

Mainland Chinese immigration authorities issued 133 million passports in 2017 and recorded more than 46 millions visits to Hong Kong and Macau by mainlanders, official data showed.

The number of mainland Chinese travelling to international destinations has plateaued in the last three to four years, McKercher said, but with China's economy expected to maintain formidable growth, a bigger portion of its population is likely to apply for passports.

“Countries such as Thailand, Japan, Korea, and Malaysia would benefit from the continuous growth of the outbound travel market of mainland China,” he said.

The Euromonitor report also forecast that China will be the top destination for international travellers by 2030 but did not provide specific estimates. Tourist arrivals in China were estimated at 67.3 million this year, seen rising by about a quarter to 88.5 million in 2023.

China’s “high-income” group is expected to expand to 480 million by 2030, accounting for more than a third of its population, according to Dan Wang, an analyst at the Economist Intelligence Unit. Barring an economic crisis, she sees this translating into more people taking trips overseas.

Wang said China's attractiveness to foreign visitors could be dimmed by its bad air quality and inefficient tourism services.

“Among travelling annoyances, transport, food quality, bathroom availability are still top concerns for foreign visitors, in addition to air pollution,” she said by email. “China’s urban and rural development strategy has been intrusive and in many ways destructive to historical and natural sites, hurting the attraction of Chinese tourism in general.”

The Euromonitor International report noted that China had the second highest CO2 emissions from transport with 851.9 million tonnes in 2017, behind the US’ 1.87 billion tonnes.

Wouter Geerts, a consultant at Euromonitor International, said in the report that China was “changing tack” and “looking at conservation, diversity of cultures and the natural environment as important aspects of a cohesive tourism offering.”