Hong Kong is losing its luster for the increasingly affluent, sophisticated mainland tourists in the coming National Day holiday.

"The passion of mainland travelers (for Hong Kong) has dampened dramatically this year," said Sarah Leung, director of the Hong Kong Tourism Industry Employees General Union.

She said the number of tour groups from the mainland during Golden Week will drop an estimated 10 percent compared with the same period last year.

The situation regarding hotel bookings is grim, with the number of reservations slumping notably, Leung added.

"Hong Kong's retail market and restaurants have taken a hard blow since the start of this year. The revenue throughout the year is projected to fall 20 to 30 percent compared with last year," Leung said. "We predict that the two industries will continue going downhill during the Golden Week due to the reduced number of mainland travelers."

China Youth Travel Service in Beijing confirmed the same trend. The number of planned trips to Hong Kong dropped 15 percent during Golden Week compared with the same period last year. The total number of visits from the mainland to Hong Kong from January to September dropped 17 percent.

For years, Hong Kong was the first choice for outbound Chinese mainland tourists. Now it's losing visitors to competitors such as Macao, South Korea, Japan, Thailand and Europe.

A 2013 report from Boston Consulting Group said Chinese mainland tourists are set to abandon Hong Kong for the wider world within a decade.

"Mainland people, especially luxury-goods consumers, have no intention to travel to Hong Kong. They've switched to European countries," said Leung, who went to Beijing recently to look into the potential tourism market. "It is Hong Kong people's hostility toward mainland tourists that has led mainlanders to lost interest and trust in Hong Kong."

Xu Xiaolei, spokesman of China Youth Travel Service, said Chinese mainland tourists' first choices are becoming more diversified as overseas destinations are improving their service to attract affluent Chinese.

"In the past, many clients would consider the language and culture barriers, distance, expense and convenience of getting a visa when planning their first overseas trip. So Hong Kong jumped out as the perfect choice," Xu said.