Leung pleaded guilty to one count of assaulting a police officer during the incident, but denied two counts of rioting and one of inciting others to riot.

Four co-defendants – Lam Lun-hing, Lam Ngo-hin, Lee Nok-man and Lo Kin-man – pleaded not guilty to a range of other charges including rioting and taking part in an unlawful assembly.

During the proceedings on the fifth floor of the court building, a witness named Miss Chan saw a man in a red windbreaker sitting next to her take out his phone to photograph the courtroom.

“He was talking to others on WeChat and has sent the photo,” she said, when the judge invited her to recount what she saw.

The court bailiffs were approached for help and when they questioned the man, they did not take a clear look at the contents of the photos. Neither did they ask him for further details when he claimed he was a tourist from the mainland.

Bricks thrown, officers attacked and a warning shot fired in video clips shown in Hong Kong court on second day of riot trial

The situation brought proceedings to a stop as the court convened a special session to decide what to do to avoid any possible prejudicial effects on the case.

The bailiff officers, when called to give their account, said they only knew the man had taken about seven or eight pictures and a short video, and these were subsequently deleted. The officers said they had warned him not to take pictures again, but did not verify his tourist status before letting him go.

Prosecutors accuse Hong Kong activist Edward Leung of inciting crowd on first day of Mong Kok riot trial

She decided to inform the nine jurors, and allowed the media to report the incident.

“It should be someone who is not familiar with the Hong Kong judiciary to have made [this] careless mistake.”

Pang said the man also took a picture of the court before the jury entered the room.

“I do not think it is targeting the jury,” she told them, asking them not to be worried

In response to queries from the Post, a judiciary spokesman said the courts had referred the matter to the police. He did not say if there was a protocol for bailiff officers to follow, and refused to comment on whether the protocol – if it existed – had been fully followed.

When the trial resumed after the drama, hawker control officers recalled how people teamed up with street vendors to clash with them during the incident.

Lai Yau-yu said it was his day off on February 8, but he went to the scene after receiving messages from police officers telling him that members of Hong Kong Indigenous – a localist group that Leung was then part of – would be there.

Assistant hawker control officer Chan Cheuk-bun said that shortly after 9pm, he saw four or five people wearing blue T-shirts bearing the words “Hong Kong Indigenous”.

They put on masks at a back alley around Portland Street. He then heard someone urge street hawkers to move to the main road, before onlookers began to hurl verbal abuse at his colleagues.

As the crowd later swelled, Cheung Man-ngai, chief hawker control officer, said he saw his colleagues being surrounded by people. A vendor, accompanied by others in blue t-shirts, charged at him with the mobile hawker stall. Cheung later clarified that the street cart did not hit him.

The trial continues on Monday.