He says they are investigating to try to work out who was behind the blast that killed at least 22 people – including 8 foreigners.
100 others were injured in the blast near a shrine that's popular with tourists.
Stephen Power, a Waterford man who’s been teaching in Bangkok for four years told media that the bombing happened in a very busy part of the city.
Investigators say it doesn't match tactics used by separatists in the south of the country.
The Thai national police chief says those who planted the device knew there would be victims.
