SEOUL (AFP) -- South Korean riot police plan to use helmets with built-in video cameras to gather better evidence against violent protesters, a report said Wednesday. Police already use video clips and photos of demonstrators to bring charges and now want headgear capable of capturing video footage, Yonhap news agency said. Officials at the National Police Agency refused to comment on the report. Thousands of riot police armed with helmets, shields and batons were on duty during eight days of negotiations on a free-trade agreement with the United States which ended Monday. No serious clashes were reported, unlike earlier anti-FTA protests. Last November major demonstrations left 63 people injured across the country, including 35 police officers. Civic groups have accused police of violating human rights by indiscriminately filming citizens. However some protesters wear masks to avoid being identified.