By Jonathan Head
BBC News, Bangkok
The southern conflict has claimed some 3,500 lives since 2004
Five years ago, on the morning of 4 January 2004, a group of more than 50 Muslim militants stormed an army depot in Narathiwat province.
They killed four soldiers, took more than 300 weapons and burned 20 schools.
The incident marked a dramatic escalation of the decades-old conflict in the south between ethnic Malay separatists and Thai security forces.
Until that day the official view in Bangkok was that the insurgency had dwindled to an insignificant level.
Any violence was a consequence of the struggling and organised crime rife in the region.
So confident was then Prime Minister Thaksin Shinawatra of this that in 2002 he dismantled the Southern Border Provinces' Administrative Centre (SBPAC) which had co-ordinated government policy there since 1981, and the joint military-police security arrangements.
Misinformed and mistaken
Instead, he put the police in charge. This proved a huge miscalculation.
The police stationed in the south lacked the experience and training to be effective.
Mr Thaksin and his cabinet were also poorly informed - they underestimated the rise of a new generation of young insurgents in the south, inspired by militant jihadism in other countries.
Mr Thaksin is now widely blamed for the renewed conflict, which has claimed around 3,500 lives since 2004.
After the coup that ousted him in 2006, the new military government promised a fresh approach, reviving the SBPAC.
But Amnesty International now argues that this has not improved the dire human rights situation in the south.
In a report published today it has documented a sharp increase in the use of torture by the security forces since mid-2007, when the military implemented a new battle plan to curb insurgent attacks.
Citing the cases of 34 people, the organisation says torture is now systematically used by the security forces in the south - it is not an occasional result of stressed troops overreacting.
This is despite torture being outlawed under the Thai constitution, and the government's repeated statements that it wants to win the "hearts and minds" of local Muslims.
In its report, Amnesty gives details of some harrowing incidents of torture: in one, a woman and her six-year-old son were both tortured to try to extract information about her husband.
Four of the people in the report died in custody.
Amnesty believes there are at least 21 unofficial detention centres in the south where detainees are mistreated, in addition to the two official prisons for insurgent suspects.
This, it says, makes it difficult for human rights groups to monitor abuses.
Thai soldiers face a secretive and little understood insurgency
Neither local nor international groups are allowed regular access to these centres; even the International Committee of the Red Cross is not given access.
And during the first three days of detention, when torture is most likely to occur, prisoners are routinely denied visits by relatives or lawyers.
So why is this still happening, after the chorus of condemnation, even by the Thai military, of the hard-line approach under the Thaksin administrations from 2001 to 2006?
Fear and frustration
One cause must be the fear and frustration experienced by the 30,000 Thai soldiers now stationed in the south.
The insurgency remains secretive and remarkably poorly understood.
Knowledge of its structure and key personnel is very sketchy. It never admits responsibility for attacks.
And those attacks are relentless, and brutal: civilians have been beheaded and burned alive; school-teachers and Buddhist monks targeted; soldiers and police maimed and killed by double booby-traps, in which a smaller bomb is followed by a larger explosion to hit those assisting the earlier victims.
Another cause is the flood of paramilitary units into the south, which are less accountable, and more poorly trained, than many regular army units.
"We appreciate the gravity of the insurgency that the government is facing - we understand the pressure they are under," says Benjamin Zawacki, of AI's South East Asia team.
"But there are simply no circumstances under which torture is justified."
The new government in Thailand has, once again, promised a new approach to the south.
Foreign Minister Kasit Piromya has talked about creating a minister with special responsibility for the region, along the lines of Britain's Minister for Northern Ireland.
He has promised that a new body will replace the revived, but largely ineffective SBPAC which will supervise all military activities.
But the army commander, Gen Anupong Paochinda, has expressed his opposition to this plan. As a man who played a central role in putting the current Democrat-led coalition government together, his wishes are more likely to prevail.
The new government's resolve to improve official behaviour in the south has already been given a test.
On 25 December an inquest in Narathiwat ruled that torture by soldiers was responsible for the death in March 2007 of a local Muslim Imam, Yapa Kaseng, who was being held in custody.
The inquest names the soldiers responsible.
In the five years since the conflict flared up no security forces personnel have ever been charged with abusing or killing civilians, despite numerous well-documented cases.
Human rights campaigners in Thailand argue that this inquest must now be followed by criminal charges against those named in the verdict, for the government's claims of a new approach to have any credibility.