Yuen was remanded at Lo Wu Correctional Institution after she was charged with breaching the national security law after participating in the pro-democracy camp's primary election last year.

The institution's management received intelligence recently that individuals in custody have attempted to build up forces and incited others to participate.

In the morning today, a surprise search was conducted at a workshop where a target works at. She and another five people in custody were found in possession of prohibited articles, whereupon correctional officers immediately took disciplinary action against them.

At 3.58pm, 18 inmates of the same workshop pressured the institution management to rescind the disciplinary action taken against the six or else they would retaliate with further actions.

The Correctional Services Department immediately deployed reinforcement including the Regional Response Team and Dog Unit to assist the frontline staff in removing the 18 people under investigation. The operation is still in progress.

It is understood that Woo Ying-ming headed to the scene.

Lo Wu Correctional Institution is a medium security institution for the detention of female adult convicts and remand persons in custody.