One woman was killed and 18 persons wounded, some of them critically, by a bomb place outside a Pattani noodle shop on the anniversary of the 2004 Tak Bai "incident".
The bomb tore through the noodle shop around 7pm on Monday in Pattani town, just south of Tak Bai district in neighbouring Narathiwat.
"One woman was killed, a Thai Buddhist, and 18 were injured," Yutthakarn Chitmanee, an officer at Muang Pattani police station told a reporter of the AFP news agency.
There were multiple casualties, said eyewitnesses. Many had what seemed life-threatening injuries.
The noodle shop was left a twisted wreck by the blast.
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The attack occurred the evening before the 12th anniversary of the deaths of 85 Muslim men arrested and packed into trucks by army and paramilitary forces sent to Tak Bai to break up an anti-government protest.
The victims smothered to death when "stacked like cordwood" in the backs of army trucks taking the detained, bound men to the infamous Ingkayut Borihan Military Camp in Pattani province.
A judicial inquest found the Thaksin Shinawatra government and the military responsible for the deaths. No arrests ever have been made. The "incident" has caused permanent resentment by majority Muslims in the restive region.
In all, more than 6,600 people -- most of them Muslims and civilians -- have died since the 60-year-old separatist rebellion erupted once again into violence in January, 2004. The insurgency has no identified leader, and includes numerous groups and gangs.
Since the May 22, 2014, coup, the military has taken charge of trying to suppress the revolt.
The ruling junta also claims it has tried to restart peace talks with a Malaysian group, Mara Patani, which includes the pro-violence Barisan Revolusi Nasional (BRN). No noticeable progress has been made on the political front, and the militants based in Thailand have largely stopped direct combat and switched to terrorist-type bombing attacks.
Police believe last August's Mother's Day bombings in six southern provinces were the work of the separatists and security forces in Bangkok are currently on alert after intelligence reports of a possible attack by a car bomb or pipe bombs.