A Hong Kong Magistrates' Courts on Tuesday adjourned the trial of a 25-year-old man who was charged with one count of assaulting police officer and one count of possessing explosive substance.

The case will be heard on Dec 3, pending the government's analysis report on the explosive materials.

The defendant, Cheong Hon-tung, a former security guard, who appeared in court today, was arrested inside the Whampoa MTR station on Aug 11, where he was allegedly assaulted a police officer with his legs.

Cheong was carrying with him potassium nitrate and sugar, two typical ingredients for making smoke bombs.

Possessing explosive substance is liable to imprisonment for up to 14 years.

Another defendant, 22-year-old Andrew Yiu Tsz-ho, appeared in court together with Cheong. He was arrested in the same station with Cheong and was charged with the possession of offensive weapon in public place. The offense is liable to imprisonment for up to three years.

His case will also be heard on Dec 3.

Both Cheong and Yiu were released on bail and required to observe curfew orders.

Separately, Hong Kong Police Force arrested four people in violent protests in Yuen Long on Monday night.

One 17-year-old man was arrested for unlawful assembly, and violating the newly-enacted Prohibition on Face Covering Regulation under the Emergency Regulations Ordinance.

Hong Kong enters the 19th consecutive week of violent protests against the now-withdrawn extradition law amendment.

Since June 9, 2,363 suspects have been arrested in numerous violent protests in Hong Kong.