Beijing on Wednesday warned Manila not to "further harm bilateral relations" in response to Manila's repeated provocations, which have worsened the month-long Huangyan Island impasse.

Analysts said upcoming anti-China demonstrations, encouraged by the Philippines, will increase tension and hostility between peoples of both countries.

The Philippine side recently urged both its domestic public and overseas citizens to launch protests and demonstrations aimed at China, the Chinese Foreign Ministry said on Wednesday.

A Philippine civic organization also announced plans to hold a series of protests on Friday in front of Chinese embassies and consulates in some major cities worldwide, according to the Philippine television network ABS-CBN.

"Such moves have triggered a strong response from Chinese people, both domestic and overseas. China calls on the Philippines not to further harm bilateral relations," Foreign Ministry spokesman Hong Lei said at Wednesday's daily news conference.

The Philippine side made a series of tough remarks in regard to the island incident and inflamed the public mood in the Philippines, which "seriously damaged the atmosphere of bilateral relations", Hong said in response to questions about the possibility of further escalation.

Yang Baoyun, a professor of Southeast Asia studies at Peking University, warned that Manila's decision to stir up nationalist feelings within the country is to seek greater support from voters at the cost of China-Philippine bilateral relations.

"The Philippine government is trying to play up the island dispute to shift the focus of its public from the domestic economic downturn and other instabilities," Yang said.

China's embassy in the Philippines has issued a safety alert for Chinese enterprises and nationals in the country ahead of massive protests against China.

The embassy's notice said that "massive anti-China demonstrations" are about to happen within days, and Chinese nationals are advised to be on alert and avoid going out, according to the Tuesday notice issued by the embassy's economic and commercial section.

It also urges Chinese nationals to stay away from protesters, keep a low profile and abide by local laws.

Beijing is still willing to show the "greatest sincerity" to resolve the island impasse through diplomacy with Manila, a senior Chinese diplomat said on Tuesday.

"We have a thousand reasons to ensure and develop the bilateral traditional friendship," Deng Zhonghua, director of the department of boundary and ocean affairs with the Ministry of Foreign Affairs, said in an interview with Phoenix TV.

Deng reiterated that the island has been China's indisputable territory since ancient time, and the waters around the island have been Chinese fishermen's traditional fishery.

Philippine media on Tuesday said that Filipino fishermen told the local government that Chinese vessels were preventing them from fishing inside the island's lagoon.

"Our fishermen and fishing boats' safety must be ensured, our fishermen's dignity should not be offended and their regular fishery operations should not be interrupted or blocked," Deng said.

Philippine vessels were reportedly still in China's territorial waters on Wednesday.

Joint drilling request

Beijing on Wednesday reacted positively to a Philippine mineral company's request to jointly develop oil and gas resources at Liyue Bank of Nansha with China National Offshore Oil Corp.

Hong reiterated that Liyue Bank is a part of China's Nansha Islands, over which China enjoys indisputable sovereignty.

Any unilateral development by the Philippine side will violate China's rights and interests, Hong said.

"Beijing is willing to talk with Manila about the joint development, and the key is that the Philippine side should be sincere," the spokesman added.

zhangyunbi@chinadaily.com.cn