China demanded Thursday that US diplomats based in Hong Kong "stop interfering" in the city's affairs, after reports that they met with pro-democracy activists, prompting a furious response from Washington.
China's foreign ministry had expressed "strong dissatisfaction" with US authorities, citing local media reports that a US official from Hong Kong's US consulate general had met with a local "independence group".
In a statement Thursday, the ministry urged the diplomatic office to "immediately make a clean break with various anti-China rioters" and "stop interfering in Hong Kong's affairs immediately".
A report in Hong Kong newspaper Takungpao said there had been a meeting between members of the political party Demosisto -- including prominent democracy activist Joshua Wong -- and Julie Eadeh, political unit chief of the US consulate general in Hong Kong.
Speaking to reporters in Washington, State Department spokeswoman Morgan Ortagus rejected China's claims and accused it of leaking personal details of their diplomat.
"I don't think that that's a formal protest, that is what a thuggish regime would do," she said. "That is not how a responsible nation would behave."
"Our diplomat was doing her job and we commend her work," Ortagus added. "This is what American diplomats do every single day around the world."
A State Department official had earlier in the day told AFP representatives of the US government "meet regularly with a wide cross-section of people across Hong Kong and Macau."
"For example, the day of this particular meeting, our diplomats also met with both pro-establishment and pan-democratic camp legislators, as well as members of the American business community and the consular corps," the spokesperson said on condition of anonymity.
Beijing has increasingly pitched the anti-government protests in the semi-autonomous region as funded by the West but has provided little evidence beyond supportive statements from some Western politicians.
Tensions are high in the Asian financial hub after two months of protests and clashes triggered by opposition to a planned extradition law that quickly evolved into a wider movement for democratic reforms.
Demosisto says it campaigns for more self-determination for Hong Kong but not independence.
Last year, the Hong Kong National Party was outlawed on the grounds it posed a security threat, the first such ban since 1997.