SHANGHAI -- The Chinese foreign ministry on Friday informed the U.S. embassy that it had revoked authorization for the American consulate general in the southwestern city of Chengdu.
The move comes in response to Washington's closure order on Tuesday to the Chinese consulate in Houston.
"The measure taken by China is legitimate and necessary response to the unjustified act by the U.S.," the foreign ministry said in a statement on its website. "It conforms with international law, the basic norms of international relations and customary diplomatic practices."
Speaking at the ministry's daily late afternoon media briefing, spokesman Wang Wenbin, said, "Some members of the U.S. Consulate General in Chengdu are engaged in activities incompatible with their status, interfering in China's internal affairs and undermining China's security interests."
"China has made representations on this many times," he added, without offering detail.
The foreign ministry did not spell out how soon the U.S. consulate would have to be vacated. Global Times, an affiliate publication of the Communist Party's flagship People's Daily, cited an unnamed source who said Beijing had given the U.S. until Monday to empty the mission.
"The U.S. is responsible for all this," the foreign ministry said. "We once again urge the U.S. to immediately retract its wrong decision and create necessary conditions for bringing the bilateral relationship back on track."
The U.S. had given China just three days' notice to evacuate its diplomatic outpost in Houston. Chinese diplomats and local media had warned that Beijing would retaliate for the move against the Houston mission, which U.S. Secretary of State Mike Pompeo on Thursday called "a hub of spying and intellectual property theft."
Julian Ku, a law professor at Hofstra University in Hempstead, New York who focuses on China's relationship with international law, noted his puzzlement on Twitter with Beijing's reasoning.
"China keeps saying the US violated intl law when it ordered the closure of the Houston Consulate, but China's closure of the Chengdu Consulate is perfectly legal," he said. "It's not clear what intl law the US violated?"
Stock markets in Hong Kong and mainland China, which had already been trading lower, sank faster after news of the Chengdu closure order. The CSI 300 index of Shanghai and Shenzhen stocks ended down 4.4% while Hong Kong dropped 2.2%.
Cai Wei, China's consul general in Houston, told U.S. publication Politico in an interview published Thursday that as he was contesting Washington's closure order, he would keep the mission open "until further notice" but added, "We will see what will happen tomorrow."
The Chengdu mission played a role in the scandal that brought down Bo Xilai, the disgraced former rival to President Xi Jinping: a top police official and deputy to Bo in 2012 sought asylum at the consulate, which is also used by the U.S. to monitor the sensitive situation in Tibet. The consulate, opened in 1985, is staffed by about 200 employees, according to its website.
The tit-for-tat closure orders come amid escalating tensions between the world's two biggest economies. U.S. President Donald Trump had said Wednesday that he might order other Chinese missions to shut too.
Additional reporting by Zach Coleman in Hong Kong.