Police in Thailand have arrested two people after bomb attacks they say stem from internal conflict left four dead yesterday.
Four bombs exploded in the resort town of Hua Hin, while several blasts hit the island of Phuket, a top tourist destination, all within 24 hours.
Four people were killed in the attacks, and 20 injured including three Germans, three Italians, an Austrian and three Dutch nationals.
Police detained two men for questioning over the blasts.
They said the blasts were "acts of sabotage" stemming from internal conflicts and not linked to international militants.
Thai Prime Minister Prayuth Chan-Ocha suggested opposition forces were behind the blasts.
"There are people who've tried to stir up a situation before referendum day, and again on this important day for Thais.
"We the government will investigate this and with our utmost efforts bring whoever is responsible to court."
Edwin Wiek runs a wildlife protection charity near the tourist town of Hua Hin, and raced to the scene a half hour after the first blast.
He said it seemed foreigners were being targeted.
"There's lots of bars, clubs and music places where people go for a drink, listen to music and then hang out and go for a massage.
"It is typical where all the foreign tourists really go, so it looks like they were aiming to get as many foreigners as possible."
Mr Wiek said later explosions in Hua Hin were also at a popular tourist spot, this time a clock tower where bus and taxi day trips run from.
Hua Hin is about 200km south of Bangkok while the province of Phuket is in the far south.
Both places, as well as Phang Nga are known for their scenic beaches. In Surat Thani, there were two explosions in front of police stations half an hour apart.
New Zealand's Ministry of Foreign Affairs and Trade advised citizens in Thailand to be vigilant, monitor the media for updates, follow the instructions of local authorities and keep family members abroad informed.