The three women, who all worked for a royally-sponsored farm project, were killed in an early morning drive-by shooting in Pattani, one of three insurgency-plagued provinces bordering Malaysia.

"Six suspected insurgents came on three motorcycles before opening fire on a pick-up carrying more than 10 people, including children, to work at the farm project," police said.

Three other women were injured in the attack, police said.

The killings came as junta leader Sonthi Boonyaratglin began a one-day visit to the region to meet with security officials following a series of bloody attacks that have shocked the nation.

Sonthi, the first Muslim to head the army in this mainly Buddhist nation, arrived early Monday in Yala, the scene of the most gruesome of the recent violence, including a massacre of eight Buddhist civilians and a bombing at a mosque on Wednesday.

Military officers have arrested 28 people in connection with the massacre.

Tensions were raised even further over the weekend, when two Muslim boys were killed in an attack on an Islamic boarding school in neighbouring Songkhla province.

The killings sparked a protest by 400 people living near the school, who blamed the military for the attack and blocked a road to prevent police from investigating the scene.

At least 2,000 people have been killed in separatist violence that has gripped the provinces of Yala, Narathiwat and Pattani since January 2004, with the bloodshed occasionally seeping into neighbouring Songkhla.

The military has imposed a curfew on parts of the region, where violence has surged despite a raft of peace-building measures proposed by Thailand's military-backed government.

A string of coordinated bomb blasts across the southernmost region last month killed nine and injured 44, while killings have also become more gruesome, with two beheadings in March.

Agence France-Presse