"It has recently come to my attention that the Chinese government has threatened to interfere with the work of American journalists in Hong Kong," Pompeo said in a statement.

"These journalists are members of a free press, not propaganda cadres."

Pompeo did not explicitly criticize China, nor did he give specific examples of what he was referring to, but the statement is the latest US response after Beijing expelled more than a dozen American reporters.

"Any decision impinging on Hong Kong's autonomy and freedoms as guaranteed under the Sino-British Joint Declaration and the Basic Law would inevitably impact our assessment of One Country, Two Systems and the status of the territory," Pompeo said, referring to arrangements by which Hong Kong was handed back to China from Britain in 1997, and which were designed to guarantee rights and freedoms in the semi-autonomous city.

Tit-for-tat actions against journalists have added to diplomatic tensions, with the two countries trading barbs over the coronavirus pandemic and US President Donald Trump threatening to impose fresh trade tariffs on Beijing.

In February, China kicked out three journalists from The Wall Street Journal after the newspaper ran an opinion piece on the coronavirus crisis with a headline that Beijing called racist.

Weeks later, Washington curbed the number of Chinese nationals from state-run news outlets in the United States.

Beijing responded in March by expelling more than a dozen American journalists from The New York Times, The Washington Post and the Wall Street Journal.