Beijing has strongly protested against Washington's passage and signing into law of the so-called Promoting a Resolution to the Tibet-China Dispute Act, warning it severely undermines China's interests and must not be implemented.
The act gives recognition to the notion of "Greater Tibet", a concept made up by the group led by the 14th Dalai Lama, and asks the United States government and the US Special Coordinator for Tibetan Issues to counter "disinformation about Tibet" from the Chinese government.
The act grossly interferes with China's internal affairs and violates the basic norms governing international relations, sending a severely wrong signal to "Tibet independence" forces, a Foreign Ministry spokesperson said in a statement issued on Saturday.
The spokesperson urged the US to take concrete actions to honor its commitments of recognizing the Xizang autonomous region as part of China and not support "Tibet independence".
"If the US continues down the wrong path, China will take resolute measures to firmly defend its sovereignty, security and development interests," the spokesperson said.
The Foreign Affairs Committee of the National People's Congress condemned the act on Saturday for breaking international law.
Xizang affairs are China' s internal affairs, which brook no interference by any external forces, the top legislature said in a statement.
The United Nations Charter explicitly stipulates sovereign equality and the independence of states. The Declaration on the Inadmissibility of Intervention and Interference in the Internal Affairs of States, adopted by the UN General Assembly in 1981, further emphasized the principles of sovereignty, independence and noninterference in other states' internal affairs, it said.
People of all ethnic groups in Xizang have achieved a full victory in poverty alleviation, resulting in greater social stability, economic and cultural prosperity, a better environment and happier lives, the statement said.
Any attempt to obstruct people in Xizang from pursuing a happier and better life will end in vain, and efforts to contain and suppress China by destabilizing Xizang are bound to fail, it added.
At a symposium on Saturday, members of the Committee of Ethnic and Religious Affairs of the Chinese People's Political Consultative Conference National Committee slammed the act for being fraught with extremely erroneous views and provocative remarks.
Under the guise of ethnicity, religion and human rights, the act blatantly meddled in China's internal affairs, they said.
The committee members accused the US and the Dalai clique of brazenly denying China's sovereignty over Xizang, saying such acts are typical examples of US-style bullying that greatly offend the Chinese people.
As the Chinese government implements the policy of freedom of religion, respects and protects religious traditions, and manages religious affairs in accordance with the law, they said the US is in no position to make unwarranted remarks.
The Standing Committee of the People's Congress of the Xizang Autonomous Region slammed the act for advocating a "Greater Tibet", saying it lays bare its true nature and sinister intention of containing and suppressing China, and attempting to internationalize the so-called Tibet issue.
The so-called Tibetan government-in-exile is an out-and-out separatist political group and an illegal organization violating China's Constitution and laws, the regional legislature said in a statement.
The 14th Dalai Lama and the so-called Tibetan government-in-exile have no right at all to represent people in Xizang, let alone decide the future of the autonomous region, it said, adding that manipulation by US anti-China politicians will in no way sabotage the stability in Xizang.
The Xizang Autonomous Region Committee of the CPPCC said no matter how the US tries to confuse right and wrong, it cannot change the fact that Xizang has been an inalienable part of China since ancient times.
People of all ethnic groups in Xizang firmly support any measures taken by the Chinese central government and will fight against any separatist forces, the regional political advisory body said.