BEIJING -- China on Friday slammed the United States and the Philippines for conducting joint patrols in the South China Sea, saying the move produced tensions and undermined peace and stability in the region.

Foreign Ministry spokesperson Lu Kang made the remarks at a routine press briefing in response to reports that US Defense Secretary Ash Carter on Thursday revealed that the United States and the Philippines had started joint sea and air patrols in the South China Sea in March.

"This move by the United States and the Philippines has poisoned relations between countries in the region, aggravated regional disputes, triggered tensions and undermined peace and stability in the South China Sea," Lu said.

"It just goes to show who the real backstage planner of the militarization of the South China Sea is," Lu said.

The Defense Ministry also accused the United States and the Philippines of militarizing the South China Sea by conducting joint patrols.

In a statement Thursday, the Defense Ministry urged the United States and the Philippines not to impair others' interests when conducting their military cooperation, adding that the Chinese military was paying close attention to the situation and would "resolutely defend China's territorial sovereignty and maritime interests."