Chinese mainland travel agencies have stopped sending tour groups to the Philippines due to concerns for tourists' safety.
Some Web users called on tourists to boycott the island country, which has famous island destinations such as Boracay and Cebu.
China CYTS Tours Holding Co, a major travel service provider on the mainland, said that chartered direct flights between Beijing and Boracay Island every five days will be suspended starting on Sunday.
On Thursday, a Philippine Airlines flight scheduled to leave Beijing at 1:50 am for Manila was canceled, according to a notice on the Beijing Capital International Airport's website, which did not give a reason.
Two other flights to the Philippines on Thursday departed as planned.
In various statements, CYTS and other major travel agencies - in cities including Beijing, Shanghai and Hangzhou - said they have stopped sending tour groups to the Philippines.
Those who have already paid for the Philippines-bound tours will get a full refund including the visa fee, they said.
Lin Wenzhen, manager of outbound travel in the Asia-Pacific region at the Fujian branch of China Travel Service, said travel agencies had taken spontaneous action out to consideration for tourists' safety.
"Although the national tourism authority has not yet banned Philippine-bound tourism, we have adopted this proactive approach to prevent high risks to travel safety in the country," she said.
The Chinese embassy in the Philippines issued a safety alert on Wednesday, saying "massive anti-China demonstrations" are about to be held within days, and Chinese nationals are advised to be alert and avoid going out.
Dao Shuming, head of the Shanghai tourism bureau, said on Thursday that travel agencies on the Philippines told mainland counterparts that Chinese tourists should avoid going there for now because it could be unsafe for them in the Philippines.
Travel agencies will incur some losses because of the suspended business, industry insiders said.
Ge Lei, marketing manager with CYTS, said that the company will take some losses from refunds on visa fees to more than 100 tourists who booked tours to Boracay.
But industry insiders said the Philippines will lose an important source of tourists. China surpassed Japan in January to become the third-largest tourist source for the Philippines.
Travel agencies now recommend tourists go to substitute destinations in Thailand, Malaysia or Singapore, which are considered much safer, Lin, of China Travel Service, said.
Lin said recent incidents will further dampen the Philippines' popularity with Chinese tourists, which was already declining since the bloody hostage-taking incident on a hijacked bus in Manila in 2010 in which six tourists from Hong Kong were killed.
On Thursday, many netizens voiced support for proposals that called on tourists to not visit the Philippines.
"Though I recommended Boracay before, I have to say now, please, give up the idea of going there," said a netizen called "Xingzou40guo", who claims to be a traveler and writer with more than 240,000 followers at Sina Weibo, China's most popular micro blog service.
"It is not just about safety. More important, we must show our attitude! If you really like beaches, go to friendly places such as Fiji Islands, Vanuatu, and Maldives," he said.
How many Chinese tourists are now in the Philippines is not known.
Ge with CYTS said the company keeps contact with 16 Chinese tourists in Boracay, and so far their itineraries have not been interrupted by the Huangyan Island tensions.
Shanghai tourism bureau chief Dao Shuming said there are 497 Shanghai tourists in the Philippines now.
"I hope they will come back as soon as possible," he said.
Tan Zongyang in Xiamen, Fujian province, and Shi Yingying in Shanghai contributed to this story.