A man and his wife were shot dead while riding a motorcycle to work in a rubber plantation in Yala, one of the three predominantly ethnic Malay Muslim provinces with a deep history of rebellion to the rule of faraway Bangkok.

In a separate attack in neighboring Pattani province, a policeman was fatally shot by unknown gunmen while traveling to work. He later died in hospital, police told reporters.

More than 4,000 people have been killed in the last six years in the rubber-rich region bordering Malaysia, which was a Muslim sultanate until annexed in 1909 by Thailand, which many locals say has long treated them like second-class citizens.

The shadowy rebels are assumed to be separatists and often target people associated with the Thai state, like police, soldiers, government officials and school teachers.

No credible group has claimed responsibility for the violence, or stated any demands and at least 30,000 troops based in the region have made little inroads toward quelling the unrest or identifying those leading the rebellion.