Amnesty International called for an investigation into police actions against protesters in Hong Kong and urged the Hong Kong government to encourage Beijing to safeguard protesters' right to peaceful assembly.
"Ordering an independent and effective investigation into police actions would be a vital first step," Joshua Rosenzweig, head of Amnesty's East Asia regional office, said in a report.
"Authorities need to show they are willing to protect human rights in Hong Kong, even if this means pushing back against Beijing's 'red line'."
In 2017, Chinese President Xi Jinping warned in a speech marking the 20th anniversary of Hong Kong's handover to Beijing that any attempt to undermine China's sovereignty was a "red line" that would not be tolerated.
What started as protests over a now-shelved extradition bill that would have allowed criminal suspects to be sent to mainland China for trial have evolved into broader calls for greater democracy and an independent inquiry into police actions.