One schoolgirl was killed and four others were injured, two critically, in a roadside bomb explosion in restive southern province of Pattani on Saturday, Bangkok Post online reported.

The five secondary school students were travelling home from school on three motorcycles after finishing their examinations when the home-made bomb buried near the road went off on Saturday morning.

The incident took place on the Basaair-Nagate road of Pattani's Yarang district.

Hapueso Sadeh, 18, a grade six student, died instantly. She was hit by shrapnel in the head, face and torso, said Pol Col Tuande Chutanant, chief of Yarang police station.

The injured victims, all from the same school, are Mariyae Sadeh, 16, the younger sister of the dead victim and Mariyae Dueramae, Maseeto Salaema and Aresoh Salaema, all of whom are 16 years old. They were taken to Yarang hospital.

Witnesses told police that the bombers had intended to attack soldiers on a bus that was travelling in front of the students' motorbikes, but the bomb exploded just after the bus had passed the spot.

Police blamed separatist militants for the bombing.

The Pattani attack followed the killing earlier on Saturday of a rubber tapper in an ambush in Yala's Raman district early Saturday morning.

Since the resurgence of insurgency in 2004, around 11,000 violent incidents instigated by secessionists in the Muslim- dominant southernmost provinces of Yala, Pattani and Narathiwat happened, with almost 5,000 people killed and nearly 8,000 injured.