Chinese state media accused the Philippines on Monday of repeatedly infringing on China's territory in the South China Sea, spreading false information and colluding with extraterritorial forces to cause trouble.
The Philippines has relied on U.S. support to continually provoke China, with such "extremely dangerous" behaviour seriously harming regional peace and stability, China's Communist Party mouthpiece, the People's Daily, wrote in a commentary on Monday.
The Philippines foreign ministry and a national task force handling the South China Sea did not immediately respond on Christmas Day to requests for comment on the report.
Tensions between Beijing and Manila have heightened in recent months as both sides trade accusations over a spate of run-ins in the South China Sea, including charges that China rammed a ship this month carrying the Philippine armed forces chief of staff.
China claims most of the South China Sea, parts of which are also claimed by the Philippines, Brunei, Malaysia, Taiwan, Vietnam and Indonesia. An international tribunal in 2016 invalidated China's claim in a ruling on a case brought by the Philippines, which Beijing rejects.
In an unusually direct warning, Chinese Foreign Minister Wang Yi said last week any miscalculation in the dispute with the Philippines would bring a resolute response from China, and called for dialogue to address "serious difficulties".
The souring of bilateral ties coincides with Manila's moves to bolster military relations with Japan and the United States, its former colonial power and defence ally of seven decades.
China expressed anger at the U.S. this month for sending a navy ship into waters near the disputed area where China and the Philippines have had several maritime confrontations.
Washington has frequently used its defence treaty with Manila to "threaten" China, blatantly supporting Philippine violations of Chinese sovereignty and "peddling security anxieties", the People's Daily said.
That is "extremely irresponsible and dangerous", said the commentary, written under the pen name Zhong Sheng, or "Voice of China", often used to offer the newspaper's views on foreign policy matters.
Mao Ning, a foreign ministry spokesperson, said at a regular news conference on Monday: "China will not weaken in its resolve to protect its territorial sovereignty and maritime rights and interests.
"That said, China's door of dialogue remains open. We are ready to work with the Philippines to properly handle maritime issues through negotiation and consultation."
