The 24-year-old Muslim was shot dead and his mother was injured as they rode a motorcycle to a rubber plantation in Pattani, one of three southern provinces roiled by violence that has killed 3,200 people since 2004.

In a nearby district, two Buddhist truck drivers were shot dead and mutilated by four unknown gunmen at a rubber factory, police said.

The killers sped away on two motorcycles with one of the victims' amputated arms, police said.

Pattani and the neighbouring provinces of Narathiwat and Yala, abutting Malaysia, were a Muslim sultanate until annexed a century ago by predominantly Buddhist Thailand.

Around 80% of people there are Muslim and speak a Malay dialect, not Thai.

The violence has ranged from drive-by shootings and bombings to beheadings, and appears to target both Buddhists and Muslims associated with the Thai state, such as police, soldiers, government officials and teachers.

Since it erupted in 2004, the rebels have never revealed themselves publicly or claimed responsibility for the violence, which has remained limited to the rubber-producing region.

There has been no evidence to suggest direct links with international militant groups such as Osama bin Laden's al Qaeda or its regional affiliate, Jemaah Islamiah. -- REUTERS