China urges the Philippines to earnestly uphold the spirit of the joint communiqué of establishing diplomatic ties between China and the Philippines, adhere to the one-China principle, and stop wrong words and deeds on issues relating to Taiwan, a foreign ministry spokesperson said on Thursday.

Spokesperson Mao Ning made the remarks at a regular news briefing in response to a reporter's question that the Philippine Defense Secretary on Wednesday accused the Chinese Foreign Ministry of insulting President Marcos Jr. during a news briefing earlier this week.

On Tuesday, regarding Philippine President Marcos's message of congratulations to Lai Ching-te, Mao said Marcos' remarks seriously violated the one-China principle and the joint communiqué on the establishment of diplomatic relations between China and the Philippines, seriously breached the political commitments made by the Philippines to China and grossly interfered in China's internal affairs.

Mao said on Thursday that the Taiwan question is at the core of China's core interests and bears on the sentiment of the 1.4 billion Chinese people. The remarks of the Philippine side seriously violate the one-China principle and the joint communiqué of establishing diplomatic ties between China and the Philippines, seriously go against the Philippines' political commitments to China, and blatantly interfere in China's internal affairs.

"It is completely legitimate and necessary for China to state its solemn position," she said.

"The one-China principle is a red line as well as the bottom line," Mao said, adding that China will never accept anyone making provocations on the Taiwan question and will resolutely fight back.