He said such behaviour could constitute the offence of engaging in seditious acts under the city’s domestic national security law, which is punishable by up to seven years in prison.

Earlier this month, a 27-year-old man became the first person charged under the law for allegedly wearing seditious clothing in public.

Chu Kai-pong appeared in West Kowloon Court on June 14 to face three charges after he was accused of having worn a T-shirt calling for the city’s “liberation” and a yellow mask with “FDNOL” printed on it, an apparent reference to the “five demands, not one less” protest slogan that was popular during the 2019 social unrest.

National security police on Tuesday charged a 29-year-old man who allegedly wrote words on the back of bus seats to incite hatred towards the local and central governments.

The Post also learned that since the enactment of the Safeguarding National Security Ordinance earlier this year, frontline officers at various control points had been instructed to take action on seditious clothing and received relevant training.

The legislation, designed as the domestic counterpart to the national security law Beijing imposed in 2020, was enacted in accordance with Article 23 of the city’s Basic Law mini-constitution.

The source said that anyone disrespecting the national anthem could also be arrested.

Two men and one woman were arrested on June 6 on suspicion of insulting the national anthem during a 2026 Fifa World Cup qualifier between the city’s team and Iran.

According to the force, the three allegedly turned their backs to the field or did not stand while the national anthem was playing. They were granted bail pending further investigation.

At least four groups have planned to hold public flag-waving and anthem-singing gatherings in places such as Tsim Sha Tsui on Monday, in addition to official events.

Police approval is not required as the unofficial gatherings are expected to draw fewer than 50 people each, but the force said officers would be on site to monitor the events.

Another source said officers from elite squads, such as the Counter Terrorism Response Unit, would also be deployed for the wider security arrangements on July 1.

“Some officers will be in position as early as Sunday evening,” the insider said, adding that manpower would gradually increase.

He said police would conduct highly visible patrols, especially around sensitive sites, with tactical officers equipped with pepper-ball guns and stab-proof gear.

He added that security would also be strengthened at transport hubs, train stations and busy shopping areas.

Roads around the Hong Kong Convention and Exhibition Centre in Wan Chai will be closed to traffic, with barricades placed at main access points.

Authorities will hold a flag-rising ceremony at Golden Bauhinia Square attended by government officials and other dignitaries, followed by a reception at the centre.

Police chief Raymond Siu Chak-yee said last Saturday that the force would make appropriate arrangements based on national security, safety and public order.

“We will ensure we have sufficient police manpower to allow all anniversary events during July 1 to proceed safely and orderly,” Siu said.

The sources said final deployment plans would be finalised later this week as intelligence showed there were no current threats, but police would continue to gather information.