Beijing announced the US consulate in the southwestern city of Chengdu was closed as of 10am (0200 GMT) on Monday, after it ordered the facility be shut in retaliation for China being ousted from its consulate in Houston, Texas.
Police in Chengdu restricted access to the area around the consulate on Monday morning, and four officials in personal protective gear could be seen walking towards the consulate at about 10:24am local time.
China ordered the closure of the facility on Friday after Washington last week gave China 72 hours to vacate its consulate in Houston, in a dramatic escalation of tensions between the world's two largest economies.
State broadcaster CCTV shared a video on its Twitter-like Weibo account, taken by a reporter, of the American flag in front of the consulate in Chengdu being lowered at 6:18am on Monday.
On Sunday night, a crane was seen entering the consulate compound and hoisting at least one container onto a large truck.
On Saturday evening, a worker was seen using tools including a hammer and chisel to remove fittings around a plaque outside the main entrance.
Over the weekend, removals trucks entered the US consulate and cleaners were seen carting large black rubbish bags from the building.
Relations deteriorated in recent weeks in a Cold War-style standoff, with the Chengdu mission Friday ordered to shut in retaliation for the forced closure of Beijing's consulate in Houston, Texas.
Beijing says closing the Chengdu consulate was a "legitimate and necessary response to the unreasonable measures by the United States", and has alleged that staff at the diplomatic mission endangered China's security and interests.
Washington officials, meanwhile, said there had been unacceptable efforts by the Chinese consulate in Houston to steal US corporate secrets.
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