A retired teacher was killed and 13 villagers wounded when a truck bomb exploded on Thursday in Thailand's restive Muslim south, the latest in a wave of separatist violence in the region bordering Malaysia.

Police blamed ethnic Malay rebels for the bombing in front of a public health office in Pattani, one of three provinces gripped by eight years of separatist unrest.

The bomb was hidden inside a pickup truck and damaged 10 other vehicles, police said. Of the 13 wounded, three were in critical condition.

In a separate attack in neighbouring Narathiwat province, two soldiers were injured when a roadside bomb exploded during a routine patrol.

The increase in violence come amid outcry among local Muslims after army rangers in Pattani shot dead four villagers they suspected were insurgents on January 29.

More than 5,000 people have been killed since a shadowy, decades-old separatist rebellion resurfaced in January 2004 in Muslim-dominated Yala, Pattani and Narathiwat provinces.

The region, which was part of an independent Malay Muslim sultanate until annexation by Thailand in 1909, has been plagued by almost daily bombings and shootings ever since and the military has made little progress in quelling the unrest.

(Reporting by Surapan Boonthanom; Writing by Sinsiri Tiwutanond; Editing by Martin Petty and Sanjeev Miglani)