South Korean police launched a special security unit Monday as part of its efforts to bolster safety and security against possible terrorist threats, ahead of the November G20 summit in Seoul.

Police also staged a traditional martial arts demonstration along with drills showing how they will protect visitors and combat terror attacks.

They have already introduced a series of enhanced safety measures as the country prepares for the meeting on Nov. 11-12. Police announced last month that they will set up 2.2-meter security fences encircling the venue of the meeting and import " sound cannon" to disperse protesters.

A special law came into force this month allowing police greater power to restrict street rallies, with permission to mobilize the military for the purpose of suppressing protests when necessary.

The moves invited strong criticism from civic groups. Some said the sound cannon, which emits a high-frequency sound of up to 152 decibels, could cause deafness in the case of prolonged exposure.

National Police Agency Chief Jo Hyun-Oh and Sakong Il, chairman of the Presidential Committee for the G20 Seoul Summit, attended a ceremony to launch the unit.