Force insiders said the police headquarters in Wan Chai would be fenced off with two-metre-high water-filled barriers for the first time as they expected the complex and the government headquarters in Admiralty to be stormed by protesters after the march. The police building was besieged and defaced with eggs and graffiti by protesters who blocked exits and flashed laser beams at officers twice last month.

Two government sources said that the administrative wing asked civil servants on Friday to lock all confidential documents and doors, and to remove the name plates of offices before they left work in the evening, with one adding that the lifts would also be locked on Sunday.

The arrangements were made to “prepare for the worst”, one of them said.

In a response, the administrative wing said security measures at government headquarters were subject to regular review and “appropriate adjustment will be arranged as necessary”.

The Post learned that five regional response contingents, each consisting of about 600 officers, are among nearly 4,000 officers to be deployed on Sunday. The number would be higher than the 2,500 officers deployed in Sha Tin last Sunday.

Commissioner of Police Stephen Lo Wai-chung pledged in a recent meeting with four police associations to make officers’ safety a priority in response to last Sunday’s running battles with protesters in the New Town Plaza shopping centre in Sha Tin.

More than 100 elite officers from the Special Tactical Squad, known as the blue team, will be on standby. The squad comprises officers from the force’s counterterrorism division and airport security unit.

Force insiders said police would maintain a minimum presence along the route of the march to avoid frontline officers being verbally abused by marchers.

Officers from the force’s Cyber Security and Technology Crime Bureau have been tasked to monitor online forums and chat rooms used by radical groups.

“Investigation shows the police headquarters [in Wan Chai] and the government headquarters [in Admiralty] will be possible targets of protesters after the march,” one of the sources said.

To enhance security around the government headquarters, water-filled barriers were set up around the complex earlier this week. The police headquarters will be fenced off with the barriers on Saturday.

Apart from blocking invaders, another source said the giant barriers could prevent protesters from damaging security surveillance cameras and daubing the surrounding walls.

“This helps to deploy fewer officers outside the buildings and also reduce the chance of conflict between police and protesters,” the source said. He continued that “the safety of officers is our key concern”.

When asked whether the force would make a mass arrest of rowdy protesters and use a tougher approach to deal with possible unrest, the source said it would depend on the on-site situation.

Front convenor Jimmy Sham Tsz-kit said the police decision to shorten their march route was unreasonable, even though they were told it was because some internet users had threatened to engage in violent acts near the government headquarters that day.

“How can we disperse so many people in Wan Chai?” he asked.

Sham added that the front had said the march would be lawful, safe and peaceful.

He previously explained that they had chosen the city’s top court as the finishing point to underline their hope that a judge-led inquiry would restore the city’s rule of law.

Sham added on Friday that he was also upset not just with the shorter route but that police said only three westbound lanes on Hennessy Road would be opened for marchers, and that the rally must end at 9pm instead of midnight.

In previous demonstrations, six lanes on Hennessy Road were opened for marchers, and the front was allowed to end the march as late as midnight.