YALA, Thailand: Suspected militants have killed two civilians in the Thai south, while more than a dozen people including soldiers were injured in an upsurge in separatist violence, police said on Wednesday.

In troubled Yala province on Tuesday, a group of militants stormed a food shop and killed the 24-year-old owner, while three of his relatives were wounded by gunfire, police said.

Elsewhere in Yala, a 41-year-old woman whom police said worked as a government informant was shot dead.

In a spate of attacks on security forces the same day, two soldiers were injured by gunfire in an ambush by separatists in Yala, while in a nearby district a bomb and shooting attack wounded two army rangers.

In neighbouring Pattani province, seven police officers were wounded when militants hurled a hand grenade at the men as they played football.

More than 3,600 people have been killed since separatist unrest erupted five years ago in the Muslim-majority south. Tensions have simmered since Thailand annexed the mainly Malay sultanate in 1902.