Police raided an apartment in a northern suburb of the capital on Saturday afternoon and discovered possible bomb-making materials that could have been used in the evening attack in Bangkok’s bustling commercial heart.
The bomb tore through the crowded Erawan Shrine, one of the country’s top tourist attractions and close to high-end hotels and malls, killing 20 people and wounding scores more.
Among the dead were 14 foreigners, including seven from mainland China and Hong Kong.
The suspect “looks like the one we are looking for”, said national police spokesman Prawut Thavornsiri.
“They also found a lot of materials which can be used to make bombs.”
The prime suspect in the attack is a young man with shaggy dark hair dressed in a yellow shirt seen on grainy closed-circuit television footage dropping off a backpack and casually leaving the scene before the bomb went off.
Police and military personnel cordoned off the four-storey budget apartment on Saturday from scores of media and onlookers, and the arrested man could not be seen, a Reuters photographer said.
Thai television showed a photograph of a handcuffed man who appeared to be foreign, in his 20s, with a beard and hair shaven short. Reuters could not immediately verify the authenticity of the image.
Police had made little progress in the investigation into what the military government said was an attack aimed at hurting Thailand’s troubled economy.
Thai authorities had offered a $85,000 reward for information leading to the arrest of the main suspect.
Officials have had different theories about the identity of the man, saying he could be foreign, or a Thai man pretending to be foreign.
Police have been criticized for providing contradictory information, and Reuters reporters on Friday found the authorities had not checked some CCTV footage taken minutes after the blast, which featured a man dressed like the chief suspect.