Hundreds of schools in Thailand's restless south have been closed indefinitely after teachers voted to suspend classes until the security in the region is improved. They went on strike after two teachers were shot to death by unknown assailants.

Teachers in Thailand's three southernmost provinces said they would suspend classes because of continued attacks that have killed more than five hundred people in the past year. Union officials said several hundred schools Thursday did not open in one province, Pattani, and others were likely to shut in the coming days.

Four people - two teachers, a policeman and a local official - were shot to death Tuesday in separate attacks. The number of attacks has intensified since 85 people died following a demonstration, in Narathiwat province, several weeks ago, most of them Muslim protesters who suffocated while being transported by truck to detention centers.

An independent commission has completed its investigation into the incident and is to brief the Thai cabinet on Friday. Prime Minister Thaksin Shinawatra says the report will be made public and has pledged to punish those officers found responsible for the incident.

A member of the Thai Senate's special committee on the south, Kraisak Choonhavan, says the report is comprehensive but doubts that it will bring change. He notes that investigations into previous incidents have not led to security officials being punished.

"The government has to come to terms [with the fact] that demonstrations are grievances that people should be allowed to express and that they should be controlled accordingly with non-lethal weapons," he said.

An expert on the southern unrest at Bangkok's Chulalongkorn University, Panitan Wattanayagorn, says the report is not likely to please human rights groups and government critics, who feel security forces have been too harsh on the local population. But he also notes that security forces are also under pressure and have themselves sustained many casualties.

"It's a compromise, trying to bridge the gap and trying to perhaps please all groups in Thailand and this is reflecting the very complicated natures of the problem in the south," he said.

The southern region was an independent sultanate until it was annexed by Thailand one hundred years ago. The predominantly Muslim region has long felt alienated from the central government of mostly the Buddhist country and experienced a low-key insurgency in the 1970s and '80s.

The recent violence began last January with an attack on an army base in which four soldiers were killed and hundreds of arms were taken. Thai officials fear an upsurge in violence as the anniversary of the incident approaches.