YALA, THAILAND - AT least 20 people were injured when a bomb exploded on Tuesday in a busy morning market in Thailand's Muslim-majority south, where a separatist insurgency is raging, police said.

The blast came one day after militants killed and attempted to behead eight Thai soldiers in the deadliest attack in the region in more than six months.

Ten of the people injured in the latest violence were in critical condition after a bomb strapped to a motorcycle exploded at 6:35 am (7.35am Singapore time) in Yala, one of three provinces hit by the separatist violence, police said.

Police had cordoned off the area around the blast in Yala town, but had not yet searched the scene for fear a second bomb could be hidden in the market. Militants often set an explosion as a ruse to draw police to a scene, and then detonate a larger and deadlier blast once authorities arrive. The southern region was an autonomous Malay Muslim sultanate until Thailand annexed it in 1902, provoking decades of animosity toward the state. More than 2,800 people have died since the rebellion began in January 2004, with killings growing more frequent and brutal.