PATTANI, Thailand (Reuters) - A roadside bomb planted by suspected Muslim insurgents killed six Thai soldiers and wounded four on Monday in the southern province of Pattani, police said.

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A decades-old separatist insurgency in of predominantly Buddhist Thailand’s largely ethnic Malay, Muslim provinces of Yala, Pattani and Narathiwat has killed more than 6,500 people since 2004.

The latest bomb was planted on dirt road and exploded as soldiers on a routine patrol were passing, said district police chief Colonel Pruk Liangsukwho.

“It is likely the work of violent groups in the area because this area is a red area,” Pruk told reporters, referring to areas with higher levels of separatist violence.

An army spokesman was not immediately available for comment.

As with most violence in Thailand’s deep south, there was no claim of responsibility.

Violence has simmered in the three southern provinces for decades and intensified in 2004 but it rarely spills out of the deep south.

A car-bomb attack last month wounded dozens outside a supermarket in Pattani town.

Violence in the south typically rises during the Muslim holy month of Ramadan, which this year ends on Sunday.

Thailand’s military government has, since 2015, held talks brokered by Malaysia, aimed at ending the violence the process has largely stalled.