Staff at the US consulate in the southwestern Chinese city of Chengdu were busy packing belongings and removing the American insignia from the building on Saturday, a day after Beijing ordered its closure in a tit-for-tat diplomatic battle with Washington. US-China relations spiralled down this week, when the Chengdu mission was told to shut in retaliation for the forced closure of Beijing's consulate in Houston, Texas, with both sides alleging the other had endangered national security. At the Houston consulate on Friday, a group of men who appeared to be US officials were seen forcing open a back door to the facility after the 72-hour closure notice issued on Tuesday took effect. The deadline for the Americans to exit Chengdu, the capital of Sichuan province, remains unclear but cleaners were seen carting big black bags of rubbish from the consulate on Saturday. One of the sacks had split and it appeared to contain shredded paper. At least 10 bags were removed from the building in the early hours of the morning. A worker on a small crane removed a circular US insignia from the front of the consulate, leaving just an American flag flying on the now unmarked site. Other staff were seen moving trolleys around inside, one carrying a large empty metal bin, while some wheeled suitcases. Beijing said 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 and proprietary medical and scientific research. Tensions have soared between the two powers on a range of fronts including trade, China's handling of the coronavirus and a new security law for Hong Kong, with the US this week warning of a "new tyranny" from China.