China will take firm and effective countermeasures against anyone who infringes upon China's territorial sovereignty and maritime rights and interests in the South China Sea, a defense spokesman said on Saturday.

The Defense Ministry spokesman Wu Qian made the remarks in response to the spokesperson of the Philippines' National Maritime Council, who claimed that the Philippine side would not leave Xianbin Reef, and the patrol and resupply to its vessel illegally anchored there since April would continue.

In addition, the United States Secretary of Defense Lloyd Austin reiterated the US' steadfast commitment to the Philippines during a phone call with his Philippine counterpart, in response to China's legitimate actions against the Philippines' activities in the South China Sea.

Wu said that Nansha Islands including Xianbin Reef is China's inherent territory, stressing that China's rights-protection and law-enforcement operations in relevant areas are completely legitimate, lawful and professional.

"The US is not a party concerned in the South China Sea issue, and is in no position to interfere with maritime disputes between China and the Philippines, even less to undermine China's territorial sovereignty and maritime rights and interests on the pretext of bilateral treaties," he said.

The current escalation in the South China Sea situation is fundamentally caused by the Philippines, which has repeatedly made provocations and taken reckless actions, as well as the US, which has continued to fan the flame and provoke confrontation, said the spokesman.

Wu emphasized that the Chinese side will take firm and effective countermeasures against anyone who stirs up troubles in the South China Sea or infringes upon China's territorial sovereignty and maritime rights and interests.