PATTANI, Thailand -- Thai Prime Minister Abhisit Vejjajiva vowed on Saturday to end human rights abuses by security forces in the Muslim far south where a rights group said suspected insurgents are routinely tortured.

"In an area with 50-60,000 soldiers, it might happen," Abhisit said in response to allegations by Amnesty International that soldiers and police used beatings, electric shocks and simulated suffocation.

"If it is true, we will prosecute them. From now on, we will not allow human rights violations. If there are more violations, someone must be held responsible," he told reporters on his first trip to the restive region since becoming leader last month.

At least four people have died as a result of torture in the southernmost, Muslim-majority provinces, where 3,500 people have been killed in a five-year separatist rebellion, the London-based human rights group said in a report on Tuesday.

Amnesty said the government and army chiefs in Bangkok had issued frequent directives against torture but the abuse was "sufficiently frequent and widespread that it cannot be dismissed as the work of a few errant subordinates in isolated instances".

The report detailed the cases of 34 Muslims detained by police and the army from March 2007 to May 2008 in the region, an independent sultanate until it was annexed by predominantly Buddhist Thailand a century ago.

One victim described being buried up to the neck in a pit, while another talked of being made to dunk his face into sewage before having a plastic bag forced over his head.

EMERGENCY DECREE

Abhisit, whose Democrat Party enjoys popular support in the region, has promised a review of the 2005 emergency decree, which Amnesty said paved the way for serious abuses.

The decree allows officials to detain suspects without formal charges for up to 30 days, provided preliminary court approval is obtained. It also gives soldiers and police blanket immunity in the region.

The cabinet extended the decree by another three months on Tuesday, but Abhisit said it may not be renewed again.

"We are in discussions with the army and police about its effectiveness and necessity," he said in Pattani, one of four southernmost provinces hit by violence since January 2004.

Abhisit has made ending the conflict one of his top priorities, although his comments echo those of his four predecessors, none of whom made any headway.

Tensions have always been high in the provinces of Yala, Narathiwat, Pattani and Songkhla, where 80 percent of the population are Muslim and have more in common with neighbouring Malaysia, speaking a Malay dialect, not Thai.

The explosion of violence in 2004 with a raid on a military base took security forces completely surprise. Since then, the rubber-rich region has suffered daily bombings, arson attacks or drive-by shootings.

No credible group has ever claimed responsibility or stated political demands, although the targeting of symbols of the Thai state -- from teachers and monks to soldiers, police and government buildings -- leads analysts to describe the insurgents' aims as broadly separatist.