Deputy Prime Minister Prawit Wongsuwon yesterday insisted that the Central Festival Samui car bombing had nothing to do with southern insurgents wanting to expand their activities to other areas.
Gen Prawit, who oversees national security, also said authorities have now identified those involved in the bomb attack.
"We know who was involved in the bombing. Authorities are stepping up efforts to arrest them.
"Several networks linked from the North to the South were involved in the Samui bomb plot, which was well planned," he said.
Prime Minister Prayut Chan-o-cha yesterday noted the bombing occurred just ahead of the Songkran festival, which usually sees a boom in domestic tourism and arrivals of international tourists.
It is very likely the bomb plot was intended to hurt tourism and discredit the government, the prime minister said.
National police chief Somyot Pumpunmuang yesterday said police have collected enough evidence to implicate a political group in the Samui car bombing, but said arrest warrants would not yet be issued.
Pol Gen Somyot said physical evidence and witness accounts indicate that the April 10 bombing was politically motivated. He also said politicians might have arranged it, though he did not elaborate on who they might be.
Police would not rush into asking the court to issue arrest warrants until they are sure their case is watertight, Pol Gen Somyot said.
"At this stage, we will not specify whether a southern political group or any group was involved, but we are confident the attack was politically motivated or politicians were behind it," Pol Gen Somyot said.
He also said it was possible that those behind the unrest in the South might have been hired to carry out the attack.
The blast took place at 10.30pm last Friday in the basement car park of Central Festival Samui.
The seven people hurt included a 12-year-old Italian girl. The explosion damaged about 10 vehicles.