BANGKOK (REUTERS) - Eighteen people have been injured in Thailand's southern province of Yala in a string of bomb attacks by suspected Muslim insurgents upset at recent measures to rein in separatist violence, the army said on Friday.

More than 6,500 people, most of them civilians, have died in separatist violence in southern Thailand since 2004, when resistance to Buddhist rule flared up.

Thailand is predominantly Buddhist but parts of the south, particularly the three provinces of Yala, Pattani and Narathiwat, are majority Muslim, and resistance to central government rule has existed there for decades.

Fourteen bombs went off on Thursday night, followed by three more in the early hours of Friday, said Colonel Pramote Prom-in, a regional security spokesman.

The latest explosions in the provincial capital of Muang Yala, injured 18 people, five of whom still remain in hospital, added Pramote, who is attached to Thailand's Region 4 Internal Security Operations Command (ISOC). "Altogether there were 17 explosions in Yala," he told Reuters.

The military government that has ruled Thailand since a coup last May says it has adopted new strategies, including DNA swabbing, to curb the insurgency and last month pointed to a drop of 50 per cent in attacks by Muslim Malay rebels in the restive region.

But lawyers and activists say the forced DNA sweeps are further alienating residents.

The explosions were meant as a message to the Thai state from the insurgents, Pramote said, adding, "These attacks were intended to provoke."