Thai officials said Saturday they were looking for the culprits behind a string of coordinated bombings on Thursday night and Friday morning across five southern provinces. Some thirty people, including foreign tourists, were also injured in the attacks.

No one has claimed responsibility for the bombings, but the police ruled out the possibility of an international terrorist group behind the attacks. The authorities also downplayed possible links to an Islamic insurgency in Thailand's southern border region.

"There have been no arrests yet," Piyapan Pingmuang, a deputy police spokesman, told the AFP news agency.

"It is just local sabotage that is restricted to limited areas and provinces," Pingmuang told reporters Friday in Bangkok, adding that the police had yet to identify a motive.

Prime Minister Prayut Chan-o-cha called for unity in a televised address to the nation late Friday.

"Thais must help each other to restore safety and security to the nation," Prayut said. "We must join together to eliminate evil from our society."

An 'assault on the economy'

Michael Winzer, head of the Konrad Adenauer Foundation in Thailand, told DW the sites were likely deliberately chosen to assault the Southeast Asian country's economy.

"The bombings were carried out at tourist sites, so they were directed against tourism - an economic sector that has grown in recent years in Thailand and has underpinned its economy," said Winzer.

Twin blasts such as those seen on Thursday and Friday are common in the three Muslim-majority southernmost provinces of Thailand, where a bloody insurgency has killed more than 6,500 people since 2004.

The bombings came at a sensitive time in Thailand, with this weekend marking Queen Sirikit's 84th birthday. A contentious referendum put forward by the military junta was also approved last week, paving the way for a new constitution and elections next year.