The magistrate ordered the report during the last court hearing to determine whether Chiu was suitable to perform community service.

The Institute of Vocational Training student had earlier pleaded guilty to one count of assaulting a police officer.

The court heard previously that at about 8.20pm on March 1, chief inspector Lee Shek-lun was deployed to perform crowd-control duties in Yuen Long, where protesters were rallying against cross-border traders.

Emerging from a crowd, Chiu suddenly threw a blue, plastic water bottle which hit Lee’s right thigh. It was unclear whether the bottle contained water, or how much. The court heard the impact left Lee’s thigh tender. Chiu attempted to run away but Lee caught and subdued him in an alley.

Under caution, Chiu told police officers: “I did throw the blue water bottle at him. As a man, I dare to admit what I did.”

During the last court hearing, the magistrate said that however noble Chiu’s cause might be, it would be tainted by his violent acts. He asked Chiu to reflect on whether his behaviour would gain the support of the public.

In mitigation submissions, Chiu’s lawyers said he participated in the protest because the parallel traders had harmed Hong Kong’s economy, and he hurled the bottle at Lee because he saw Lee pulling the strap of a bag of a female protester.

Outside court today, Chiu, clad in a surgical mask, refused to answer questions from reporters related to his sentence.