An unknown number of gunmen shot down Mahama Jehna, 39, with M-16 assault rifles as he was riding his motorbike to help his wife at a rubber plantation near his residence in Narathiwat's Si Sakhon district.

The gunmen were hiding at the plantation and sprayed Mahama's entire body with bullets, police said.

Mahama, who also went by the alias Sahari Dahong, was a former field commander of the separatist group Barisan Revolusi Nasional (BRN). After more than a decade with the BRN, he surrendered in 2003 to the then Fourth Army Region Commander Lt-General Pisarn Wattanawongkiri, who had guaranteed his safety.

Mahama frequently travelled to Malaysia at the request of the military to convince separatists to return to Thailand and surrender in exchange for their freedom and safety.

He once told journalists he had joined the movement in 1989 after government officials accused him of involvement in several crimes that he said he did not commit. The authorities, however, prosecuted him for his alleged involvement in more than 10 violent incidents.

The authorities have been struggling to contain a flare-up of violence in the predominantly Muslim region that has been raging since early 2004. More than 1,700 people have been killed so far.

The BRN has been active since the 1960s. The group faded from view during the 1980s after the Prem Tinsulanonda administration took a soft approach to pacifying separatists and granted amnesty to a great many of them. However, many officials believe the BRN has played a role in coordinating the recent attacks.

Meanwhile, a former assistant village head was killed and a former member of a Tambon Administrative Organisation was injured in a gun attack in Yala yesterday.

Mahama Yanira was shot dead and Adulroh-o Barahamae was injured in Yala's Yaha district while driving from Mahama's home to the district's central area. Police said militants attacked the pair in order to maintain the level of violence in the region.