BANGKOK: At least 40 people were injured Tuesday when a double bombing hit a town in Thailand's insurgency-plagued south, police said, the latest suspected rebel attack to undermine stalled peace efforts.

The Muslim-majority border region has seethed with violence for over a decade as ethnic Malay insurgents battle the Buddhist-majority state for more autonomy.

The latest attack struck the town of Pattani around 2pm, with two bombs going off in quick succession outside a supermarket near the city centre.

"The first bomb was small and no one was hurt but the second bomb was huge – I don't know yet whether it's a car bomb or not," Captain Preecha Prachumchai of Pattani provincial police told AFP.

"Currently around 40 people have been wounded: one is in serious condition," he said.

Pictures posted by rescue workers on Twitter showed a thick plume of black smoke over the supermarket car park and some damage to the store entrance.

Near-daily shootings and bomb attacks have claimed more than 6,800 lives since 2004, with both sides accused of rights abuses and atrocities.