Thailand shaken by multiple bomb blasts - VIDEO
Attacks kill four people across the country, just days after adoption of contentious military-backed constitution.
Thailand has tightened security after bomb attacks across the country killed four people and wounded many more, with authorities struggling to identify a motive and find the perpetrators.
Twin bombs exploded in the upscale resort of Hua Hin late on Thursday, killing one woman and wounding more than 20 others. They were followed by two more on Friday morning that killed another person.
A further two blasts struck on Friday in the popular tourist town of Phuket, while two more bombs were reported in the southern provinces of Trang and Surat Thani, in each of which one person was killed.
Last week, Thailand voted to accept a military-backed constitution despite claims by opponents that it will entrench the military's power and deepen divisions.
Speaking to Al Jazeera from Bangkok, journalist Pailin Wedel quoted a police spokesperson as saying there is currently no evidence of any link between the different blasts.
"They are also sticking to the line that they still do not have enough evidence that there are any links to outside terrorism, southern insurgency or anything that may be linked to the current political situation," said Wedel.
Prayut Chan-O-Cha, the prime minister, called for calm and said he did not know who was behind the attacks.
"The bombs are an attempt to create chaos and confusion," he said in a conversation with reporters. "We should not make people panic more."
"Why the bombs occurred as our country is heading towards stability, a better economy and tourism - and who did it - you have to find out for me."
The two bombs that went off in Hua Hin on Thursday evening were hidden in potted plants and went off within 30 minutes of each other in the bar district of the popular beach town.
While small bombings are common in Thailand during periods of heightened political tension, there have been few such incidents in the past year and it is rare for touristic areas to be targeted.
Hua Hin is home to the summer palace of Thailand's royal family and the blast came on the eve of Queen Sirikit's 84th birthday and just before the first anniversary of a Bangkok shrine bombing that killed 20.
Authorities were searching for leads on the attackers and a motive behind the latest blasts.
According to staff at local hospitals, German, Italian, Dutch and Austrian nationals were among the wounded.
Thailand is expecting a record 32 million visitors in 2016, with the tourism industry a bright spot in an otherwise lacklustre economy.
Anniversary of attack
The latest blasts came just days before the first anniversary of the last major attack on tourists in Thailand - an August 17 bomb that killed 20 people, mostly ethnic Chinese tourists.
The blast struck a crowded Hindu shrine in the heart of Bangkok and stunned the country as the deadliest assault in recent history.
Two Uighur men from western China have been accused of the attack and are due to go on trial later this month.
Both deny any involvement in the bombing and mystery continues to swirl around the case, with authorities failing to catch a number of other suspects or offer a thorough explanation for a motive.
Thailand's military junta, which seized power in 2014 after a decade of at times violent political unrest, has touted an increase in stability in the kingdom as a major accomplishment of its rule.
Yet the generals have failed to quell a long-running conflict in Thailand's three southernmost provinces - a region far from Bangkok or Hua Hin.
The conflict is largely contained to the mostly Muslim far south although violence has occasionally spilled into other areas.
Speaking to Al Jazeera from Hua Hin, Thitinan Ponsudhirak, director of the Institute for Security and International Studies at Chulalongkorn University, said: "I think the timing is striking here. Today is the 84th anniversary of the birthday of Her Majesty [Queen Sirikit].
"We had the referendum last Sunday, so it seems clear to me that this is a coordinated round of bomb attacks.
"I think this has to do with domestic politics. It has something to do with anti-regime sentiments - anti-regime people who want to send a message that they don't like the outcome of the referendum."