Elsewhere in the south, two Muslim men were shot dead overnight on Wednesday, in an attack police said was likely aimed at further inflaming religious tensions.
Police have described Wednesday's bombing as likely "an act of revenge" against the authorities for leading a a crackdown against Muslim fighters blamed for a string of increasingly violent attacks across southern Thailand.
They said the attackers opened fire on the soldiers before fleeing the scene.
The soldiers were from the Santisuk Force which is not involved with the fighting but is instead tasked with trying to win over local Islamic leaders, military commander Colonel Phiraphon Wiriyakul told reporters.
"They may have been attacked because they obstructed the movements of insurgents," he said.
He added that two suspects armed with assault rifles had been arrested.
'Tide of terrorism'
|Officials say two suspects have been arrested |
following the bombing [Reuters]
More than 2,000 people have been killed in bombings, drive-by shootings and other attacks since a Muslim rebellion flared in Thailand's three southernmost provinces of Pattani, Yala and Narathiwat in early 2004.
Although Thailand is a mainly Buddhist country, the three southern provinces are mainly Muslim and many local residents say they are unfairly treated.
Commenting on the ongoing violence in Thailand's south a senior US defence official said only a "fair and legitimate government" would be able to defeat security threats.
"We view the war on terrorism as a long-term issue. The resolution of grievances that fuel terrorism can't be solved militarily," said Brigadier General John Toolan, a senior Pentagon official in charge of Southeast Asian affairs.
"It is a whole of government challenge and will take all our governments' efforts together to stem the tide of terrorism."
The comments elicited an assurance from Bangkok that democratic elections will be held as scheduled.
Krit Garnjana-Goochorn, Thailand's new ambassador to Washington, said both countries shared the same goal of seeing an election by year-end.
In recent years, soldiers and Buddhist civilians have become prime targets of Muslim fighters intent on driving them out of the area, and rousing animosity between followers of the two religions.
Lieutenant-General Sirapong Boonpat, the deputy secretary-general of Thailand's National Security Council, admitted that the "complicated and multidimensional" insurgency has become a serious problem.
"Nevertheless, we cannot be complacent," he said.
Noting that that violence had intensified since last year's coup, he said security services had "had difficulties identifying the ringleader behind the violence".
The number of fighters and sympathisers in the southern provinces has also grown 100-fold to about 10,000 over the last three years, added Sirapong.