Two members of the Thai security forces were killed and four others injured in two bombings in southern Thailand on Friday.

In the first incident about 10am in Yala, a policeman was killed while another was seriously injured when a homemade bomb exploded while four policemen were patrolling on two motorcycles in Yaha-Kabang road.

The 15kg bomb was set in a metal box placed at a road-shoulder in Kampung Bendang Dama, Kabang in Yala Province, said Yala police deputy chief Pol Col Banlue Shuvet.

In the second incident in Narathiwat, a ranger died and three others were injured when a bomb placed on a motorcycle by a road-shoulder went off just as the four were passing by in a truck in Takbai-Narathiwat road in Kampung Banmai, Muang Narathiwat district.

Muang Narathiwat police chief Pol Col Somporn Meesuk said the motorcycle in which the bomb was placed, was reported stolen on July 13 in Takbai, Narathiwat.