China has closed its consulate general in Houston as ordered by the United States, the U.S. State Department said Friday after labeling the mission "a hub of spying and intellectual property theft," signaling that tensions between the world's two major powers have risen to their highest level in decades.

In retaliation, the Chinese government has compelled the United States to shut its equivalent liaison office in the southwestern city of Chengdu in a development that could hurt their future diplomatic relations.

Signs are seen at the Chinese consulate after the United States ordered China to close its doors on July 22, 2020 in Houston, Texas.(Getty/Kyodo)

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On Saturday, Chinese media reported the gate of the U.S. consulate general in Chengdu has been closed, indicating that Washington has begun work on its closure.

China and the United States, which has condemned the Communist nation for engaging in spying, have been at odds over several contentious issues, including trade, business practices, Hong Kong and the South China Sea, as well as the origins of the novel coronavirus.

Beijing has said that Washington on Tuesday "abruptly demanded that China's consulate general in Houston cease all operations and events," lambasting the United States for "seriously" violating international law.

The United States reportedly gave China 72 hours to close the consulate general in the southern state of Texas, with Beijing acknowledging it has imposed the same conditions on Washington.

The consulate general in Chengdu is responsible for watching movements in areas like Tibet, invaded by Beijing in 1950, as Chinese President Xi Jinping has vowed to fight against "separatism" in the restive region.

If the U.S. liaison office is closed, Washington would lose effective ways to obtain information about human rights affairs in Tibet and China's military deployment in the western region, diplomatic sources said.

On Wednesday, the administration of U.S. President Donald Trump said in a statement that the closure of the Chinese consulate in Houston had been ordered "to protect American intellectual property and Americans' private information."

Trump said at a press conference later in the day that it is "always possible" to shut more Chinese diplomatic missions in the United States amid accusations of spying.

Earlier, U.S. media reported, citing the Houston Police Department, that documents were being burned in the courtyard of the consulate general in the city on Tuesday night.

Washington has suggested that activities such as destroying classified materials may have taken place there.

U.S. authorities have recently indicted two Chinese hackers suspected of stealing hundreds of millions of dollars' worth of trade secrets and other valuable information from firms worldwide, and also targeting companies developing vaccines for the new virus.

Sino-U.S. ties have been markedly deteriorating since China started to voice its intention to enforce a national security law in Hong Kong, raising concerns that human rights and freedoms in the former British colony would be further undermined.

Late last month, the National People's Congress Standing Committee, China's top legislative body, enacted the security law banning acts of secession, subversion, terrorism and collusion with foreign forces in Hong Kong.

Under China's "one country, two systems" policy, Hong Kong was promised it would enjoy the rights and freedoms of a semiautonomous region for 50 years following its return to Chinese rule in 1997.

On July 14, Trump signed an order to fully end the special treatment extended to Hong Kong under U.S. law, saying that he will hold China accountable for its "oppressive actions" against the people of the region.

Some believe Trump is getting tough on China in a bid to gain public support in the run-up to the presidential election in November, as political unrest has been mounting at home.

The president has announced that the United States will withdraw from the World Health Organization, labeling the Geneva-based U.N. agency a Chinese "puppet" and criticizing it for pushing Beijing's "misinformation" about the coronavirus outbreak.

The U.S. government has also recently labeled Beijing's claims to offshore resources across most of the South China Sea "completely unlawful."