BANGKOK: A pre-dawn raid on a Thai military base ended with 16 Muslim insurgents killed on Wednesday in the deadliest violence in the country's south in nine years, marking a dangerous escalation in one of Asia's least-known conflicts.

Acting on a tip-off, marines lit flares and opened fire as up to 60 insurgents wearing military fatigues approached the base at about 1 a.m. in Narathiwat province on the Malaysian border, said Internal Security Operations Command spokesman Pramote Phromin.

He revised the death toll to 16 from an earlier 17. None of the Thai military defenders of the base was hurt, he said.

Violence is common in Thailand's south but the scale of the attack and targeting of a marine base illustrate the difficulty Buddhist-majority Thailand faces in preventing the low-intensity Muslim insurgency from turning into a more dangerous conflict.

Although there is no indication of the fighting spreading beyond the provinces of Pattani, Yala and Narathiwat, just a few hours' drive from some of Thailand's most popular tourist beaches, Prime Minister Yingluck Shinawatra appears powerless to quell the almost daily gun fights and bomb attacks.

"It was only going to be a matter of time before this type of incident happened," said Anthony Davis, a Thai-based analyst at security consulting firm IHS-Jane's.

"The insurgents have been moving towards larger attacks on military bases since 2011. At the same time, there has been more pro-active security intelligence work."

The violence comes as Southeast Asia seeks to present an image of stability to foreign investors who have poured into its financial markets. The Philippines government signed in October a pact with the country's largest Muslim rebel group. Long-running communal conflicts in Indonesia have mostly abated in recent years.

A 2011 election in Thailand ushered in a period of relative stability after more than five years of sometimes-deadly street protests. Its economy is flourishing and its stock market was one of the world's best performers last year, rising 36 percent.

A political scientist with Deep South Watch, a think-tank that closely tracks the violence, said he feared the insurgents' failed attack on Wednesday would only spur them on.

"If anything, it will make them more determined because of the high casualties incurred," said the analyst, Srisomphob Jitphiromsri.

He and other experts say the insurgency is becoming better organised. Wednesday's death toll was the biggest since security forces stormed a mosque, known as the Krue Se mosque, in 2004, killing 32 Muslims in a raid that intensified the insurgency.

BOLD ATTACKS

Since then, more than 5,300 people have been killed in the three provinces of Pattani, Yala and Narathiwat where insurgents are seeking greater autonomy.

About 94 percent of the region's 1.7 million people are Muslim, the main religion in neighbouring Malaysia and in nearby Indonesia, and about 80 percent of them speak a Malay dialect as a first language, according to a 2010 survey by the Asia Foundation.

In recent weeks, attacks have appeared bolder. Five soldiers were killed by suspected insurgents on Sunday. That followed a spate of attacks on civilians, including one this month in which four fruit traders from outside the region were found shot dead with their hands and legs bound.

The government is considering imposing a curfew in parts of the south, where the military already has wide-ranging powers of search and arrest under an emergency decree.

A temporary, 24-hour curfew was imposed in four sub-districts of Narathiwat and two in Pattani from 6 a.m. on Wednesday while authorities scour the area, said Pramote.

The three provinces were once part of an independent Malay Muslim sultanate until annexed by Thailand in 1909. Muslims in the area largely oppose the presence of tens of thousands of soldiers and armed Buddhist guards in the rubber-rich region.

The violence has ranged from drive-by shootings to bombings and beheadings. It is often aimed at Buddhists and Muslims associated with the Thai state such as police, soldiers, government officials and teachers.

Most believe the attacks are organised by the Barisan Revolusi Nasional (BRN) Coordinate, an offshoot of the Patani Malay National Revolutionary Front established in the 1960s to seek independence. Another group, the Patani United Liberation Front (PULO), publicly calls for a separate state.