Thai authorities have arrested the first suspect linked to a string of bomb and arson attacks that rocked southern tourist towns last month, a police officer said Saturday.

The coordinated blasts erupted across seven provinces on Aug 11-12, killing four and injuring dozens, including foreign tourists.

No one has claimed responsibility for the bombing spree but analysts say it bore the hallmarks of ethnic Malay Muslim insurgents behind a 12-year rebellion concentrated further south.

The battle for greater autonomy from the Buddhist-majority state has killed than 6,500 people -- mainly civilians -- since 2004, but the violence rarely spills outside the southern border region.

"One suspected arsonist was arrested yesterday in his hometown in Pattani," assistant national police chief Suchart Theerasawat told AFP Saturday, referring to a province that lies in the heart of the insurgency.

The man, identified by police as 36-year-old Abdul Kadae Salae, is accused of setting fire to a supermarket in Trang province.

The flames severely damaged the building and struck during the same early morning window as bombings in other towns, including the beach resort of Hua Hin and the island of Phuket.

"He is being questioned at a military camp," the officer added.

Like some of the four other suspects still at large, Salae has a record of involvement in the southern insurgency, according police.

But officers insist it is too early to call the tourist town bombings an extension of the southern rebellion, suggesting the men could have been hired by other opponents of Thailand's military government.

Analysts say the junta, which came to power in a 2014 coup, would be loathe to admit to a major expansion of the insurgency as it would undercut their claims to have stemmed violence in the restive border region.

Drive-by shootings and roadside bombs happen almost daily in the culturally and linguistically distinct zone bordering Malaysia.

On Saturday one person was killed when an explosive planted on a railway track derailed a train car in Pattani.

"One train staff was killed and one person was injured," said Col Pramote Prom-in, a southern army spokesman.

The rebels never claim their attacks but factions are known to be frustrated with their lack of progress after more than a decade of fighting.