The lawyer of eight of the 47 defendants has been granted police bail after his arrest on Monday night at West Kowloon Magistrates' Court for obstructing officers and failure to produce identification.

Leo Yau Lut-pong, 34, is from Ng Gene-bond's legal team, whose clients include Power for Democracy convener Andrew Chiu Ka-yin, Sai Kung District Council chairman Ben Chung Kam-lun and activist Ventus Lau Wing-hong.

Another 38 people who gathered outside the court were fined HK$5,000 each for breaching the social gathering ban, while four others were fined for not wearing masks properly.

At around 10pm on Monday, Yau allegedly tried to enter the court building but was stopped by officers who asked to check court documents he was holding. Yau refused, citing privacy concerns, and after a 30-minute argument officers took him away.

"Yau was uncooperative and continued to move forward while refusing to show his ID card. Officers arrested him for obstructing police and failing to produce identification documents," police said.

Yau was detained overnight and granted bail pending further investigation. He needs to report to police by the end of the month.

Meanwhile, the US State Department said the detentions of the defendants show how the national security law is being used to stifle dissent.

At the same time, Swedish deputy consul general Joakim Ladeborn said he is concerned about the national security law.

While waiting to enter the public stand of the courtroom for the second consecutive day, Ladeborn told reporters that the court mentions were very long on Monday.

Also, AbouThai grocery store founder Mike Lam King-nam, one of the defendants, posted a drawing by his daughter Jasmine on Facebook that said: "Mama, where is my Daddy? I just want you and Daddy [to] have time to play with me, Mama!"

Separately, Zhu Fenglian, a spokeswoman with the Taiwan Affairs Office of State Council, urged the Democratic Progressive Party of Taiwan not to politically influence Hong Kong's affairs.

"The SAR government prosecuting law breachers is fully justified and should not be interfered with," Zhu said.

Leo Yau argues with police officers after allegedly trying to enter West Kowloon Magistrates' Court.

Lawyer joins action after row with cops over papers