The attack came after a police officer and a defence volunteer were shot dead in a mosque in Yala province [Reuters]
Thai authorities have alleged that drug dealers had a hand in deadly coordinated bombings in the country's south that killed four people and wounded dozens more.
Police Colonel Jakraporn Thaenthong, said on Saturday the death toll from Friday night's three bombs in the border town of Sungai Kolok climbed to four after a wounded victim died in hospital.
Jakraporn, the town's police chief, said that 13 of the more than 60 people hurt in the attack were severely wounded.
The attack by bombs concealed in a car and two motorcycles in the town bordering Malaysia was one of the biggest since Thailand's new government was installed in August.
More than 4,700 people have been killed in the Muslim-dominated southernmost provinces of Thailand since an insurgency erupted in 2004. No one immediately claimed responsibility for Friday's attacks.
"The attacks were in response to the authorities' frequent crackdown on narcotics," Jakraporn said. He added that since the new government took office in August, police have seized about 100,000 methamphetamine tablets in Narathiwat province, where Sungai Kolok is located. He said the latest anti-drug crackdown in the area took place on Wednesday.
"We believe drug dealers funded the insurgents in the case of last night's incident," he said. "They definitely aimed at harming the public, given the time and the locations of the explosions.''
The explosions took place outside a major hotel and two community centers in early evening.
A massive military effort has failed to stop the violence in the south, attributed to the secretive insurgents who advocate separatism.
On Thursday, suspected Muslim insurgents killed five soldiers and severely wounded another
in a roadside bombing in neighboring Pattani province.
Some Thai officials have long alleged ties between the drug trade and the violence, but they have offered little evidence.
Several small fires were set off by Friday's explosions. Authorities cut off mobile phone service in the area to prevent possible detonations of more
bombs, and traffic was snarled by army roadblocks.
Sungai Kolok attracts tourists from neighboring Malaysia for shopping and nightlife, including prostitution, which is less tolerated in their home
But attacks in recent years have discouraged visitors.
The previous most dramatic attack in the town came during celebrations of the 2008 New Year, when suspected Muslim insurgents set off five bombs in its hotel and nightlife area, wounding 27 people.