The United States has called on Beijing to stop its "attempts to crush press freedom" following the arrest this week of an RTHK investigative journalist.
In a brief statement, deputy spokesman of the Department of State Cale Brown said "the US is deeply concerned about the arrest”.
"The Chinese Communist Party and their Hong Kong proxies must cease efforts to crush press freedom,” Brown added.
Journalist Bao Choy had worked on RTHK documentaries on the Yuen Long mob attack last year, which revealed how police officers were present at the scene well ahead of the violence but did not intervene.
She was arrested and charged on Tuesday in relation to searches carried out on owners of vehicles that appeared to have transported some of the attackers to the town on the night in question.
On her social media account, Choy wrote that she is grateful to everyone who supports press freedom.
“Words can't express my gratitude for the help and blessing from my friends, fellows, and everyone who supports #PressFreedom,” she wrote.
The post came with a photo of a sign at the Newseum in Washington DC which says “the free press is a cornerstone of democracy” and “a free press, at its best, reveals the truth”.
Choy is due to appear in court on November 10.