A series of bombing and arson attacks in southern Thailand that killed four people and wounded dozens was orchestrated by a single person, Thai police said on Sunday, while a man has been arrested in relation to one of the attacks.
Blasts on Thursday and Friday targeted some of Thailand's best-known tourist resorts, just days after Thais voted to accept a military-backed constitution that paves the way for an election at the end of 2017.
"These acts were undertaken by a group in many areas simultaneously, following orders from one individual," Pongsapat Pongcharoen, a deputy national police chief, told reporters.
He gave no further details on who police believe was responsible for the attacks and no group has claimed them.
Analysts say suspicion would inevitably on fall on enemies of the ruling junta aggrieved by the referendum results, or insurgents from Muslim-majority provinces in the south of the mostly Buddhist country.
Bombs went off on Thursday and Friday in the upscale resort of Hua Hin and beach destinations in the south including Phuket, Phang Nga and Surat Thani, a city that is the gateway to popular islands in the Gulf of Thailand.
The wave of attacks came as tourists flocked to the beaches at the start of a public holiday. Several attacks used incendiary devices that hit shops and markets in southern Thai provinces.
A man has been arrested and was being questioned in connection to an arson attack on a supermarket in the southern province of Nakhon Si Thammarat, Pongsapat said. Police believe more than one individual was involved in that attack, he said.
The movements of other suspects were being monitored, he added.
In Phang Nga, two devices that authorities believe failed to go off were found on Saturday near a market that was torched in an attack early on Friday.
"One worked and the other two didn't," Phakaphong Tavipatana, the governor of Phang Nga, told Reuters, adding that police hoped to find fingerprints on the defused devices.