The devices were similar to those used by separatist insurgents in southern Thailand, but that did not conclusively show they were the perpetrators, he said.
He personal believed it was involved with the charter referendum because the attacks took place in the provinces that voted to approve the charter.
“Those who had different opinion may do it to discredit image of the country and hurt tourism industry,” he said.
“If you ask for my comments, I'll say they are very despicable. Aren't they Thais? I am not using rude language I am just saying they are despicable. I normally don't talk like this. But these people committed violence and caused innocent people, like vendors and women, to be injured and killed,” the police chief said angrily.