An unknown number of militants attacked a military base in troubled Pattani province early on Tuesday, sparking a 10-minute gun battle that left a 47-year-old ranger dead, said police.

A Buddhist man was killed in a drive-by shooting in the same province late on Sunday, they said.

In nearby Yala province, militants shot dead a Muslim defence volunteer and wounded two others on Monday.

Separately in Narathiwat province a police sergeant was fatally shot and another critically injured in a clash with militants early Monday.

A Muslim man was killed in a drive-by shooting later the same day in Narathiwat and his wife was wounded.

More than 3,500 people have been killed since separatist unrest erupted in southern Thailand five years ago.

Tensions had simmered since Thailand annexed the mainly Malay sultanate in 1902, but erupted into the current rebellion on January 4, 2004, when militants raided a southern army base, killing four soldiers.

New Thai Prime Minister Abhisit Vejjajiva vowed soon after he was elected by parliament on December 15 to ease the southern tensions. His Democrat Party counts the south as one of its strongholds. -- AFP