The barriers, which underwent trials during festive occasions and large crowd control operations, proved to be more stable and would not easily topple.

The Police Tactical Unit Headquarters initiated a review of the old design after receiving some reports of the old barriers toppling when under pressure.

With the assistance of designers in the CSI, a new prototype was developed and was put to test during the Fortune Global Forum, National Day fireworks display, Legislative Council meetings and Dragon Boat Race meetings.

"The Wan Chai, Central, Waterfront and Castle Peak Divisions which tried out the new barriers found them to be satisfactory," PTU officer said.

The new barriers consist of long and short modules and with self-anchoring points can be arranged in a box formation to withstand violent surge action by unruly crowds.

When arranged in a single line formation, they can stay upright even if the road surface is uneven.

The CSI is expected to deliver the newly ordered barriers next month, and there are plans to gradually replace all the old ones.