It said their actions were in line with rights enshrined in the 1997 charter.

Attorney Sermkiat Woradit said his office decided to drop six charges against PAD members, including Sondhi Limthongkul, over allegations they had undermined state order by causing violence and abusing Thaksin. The office concluded that the PAD members had the right to hold peaceful rallies under the charter.

From February 4 to March 30 last year, unarmed demonstrators from all walks of life utilised their right to protest to oust Thaksin because they had lost faith in his administration, Sermkiat said. The rallies never turned violent, he added.

Although the rallies caused traffic jams as they moved through main streets, the situation remained - for the most part - under control, he said.

Along with Sondhi, PAD leaders charged included Chamlong Srimuang, Chirmsak Pinthong, Suriyasai Katasila, Karun Sai-ngam, Rosana Tositrakul and Sirichai Mai-ngam.