Violence in Thailand's southern provinces has reached a level that shocked many when Muslim separatists attacked a van and killed nine passengers. As Ron Corben reports from Bangkok, experts say it appears the militants hope to drive non-Muslims out of the region, despite government efforts to bring peace.

Front-page headlines called it the "Massacre in Yala". Photos showed bodies on the roadside, one of them a boy wearing his school sports shoes and clean white socks.

The recent attack on a commuter van horrified many in Thailand. It occurred at eight in the morning, as the passengers made their way to the town of Hat Yai for school and work.

Muslim militants forced the vehicle off the road and shot nine passengers; the Muslim driver was spared after he pleaded for his life.

Sunai Pasuk, with the U.S. group Human Rights Watch, says the attack shows the insurgents are stepping up their campaign of terror.

"The message from the insurgents is that there will be no reconciliation, there'll be no compromise, or negotiation," Sunai said. "Buddhist Thai and ethnic Chinese are now the main targets. The idea is to terrify this group - that they are not being protected. So if you wish to live they must get out of the South."

About five percent of Thailand's 64 million citizens are Muslim. Most Muslims are ethnically Malay, and speak Malay dialects, instead of Thai. They dominate in the southern provinces of Pattani, Yala and Narathiwat, an area that was a sultanate until it became part of Thailand early in the 20th century.

The insurgents have never issued demands or identified their group. But over three years, there has been a steady slaughter - attacks on schools, government workers, farm laborers, Buddhist monks, and even Muslims accused of collaborating with the government. More than 21-hundred people have died.

Prime Minister Surayud Chulanont is under fire for failing to turn the tide of violence. He came to power after a coup last year, and has promised to peacefully end the insurgency.

He has apologized to Muslims for the hard-line approach adopted by the previous government of Thaksin Shinawatra. But so far his efforts have done little to halt the bloodshed.

The security policy organization International Crisis Group reports that the militants' capacity to deploy bombs is steadily improving.

In February alone there were 81 bombings - 37 on a single day - compared with 30 or fewer in each of the three previous months.

Francesca Lawe-Davies is the International Crisis Group's Southeast Asia analyst. She says the concern is that time is running out for the government to regain lost ground in the south.

"The government isn't able to control territory and this is a dangerous development. But I don't think we can say that they've lost the south," she said. "But they need to take serious measures to prevent that from happening and they don't have anytime to lose."

Chidchanok Rahimulla, a lecturer at Prince of Songkla University, says the separatists are increasingly confident that they will drive Buddhists and ethnic Chinese from the south. Dozens of families have already left.

"The government tries to make the peace talks but I think they cannot negotiate because the offer from the government is not what they want," he said. "They want to make the independent state and the government says no. And I think they like to show if (the government) use force it's not useful - 'We are stronger'."

But there are rising fears of a backlash by Buddhist communities.

Leaflets scattered in Yala province last year, signed by the so-called Patriotic Vigilantes, warn the group will "take action" unless the government halts the violence.

Human Rights Watch's Sunai says the emergence of Buddhist vigilantes could be a tragic turn

"Buddhist vigilante groups would be very dangerous as on a daily basis anger and frustration from the Buddhist Thai community is growing to a dangerous level. We are deeply concerned the situation in southern Thailand will escalate into the conflict between the two communities - the Buddhist Thai, the ethnic Malay Muslim."

On the evening after the van attack, grenades were thrown in a mosque in Yala (Yaha district), injuring 11 people. That led to a protest by Muslims demanding greater protection.

Islamic religious teachers said the Muslim and Buddhist communities - once closely linked - are now deeply suspicious of each other and divided - a goal of the insurgents.

The government has imposed dusk-to-dawn curfews in some districts and may expand the restrictions to other areas to prevent militants from moving during the night.

But the International Crisis Group says pure military responses will fail. It calls on the government to balance security and human rights protections.

Human Rights Watch and other groups say the authorities need to fully investigate past abuses by security forces, including the disappearances of some Muslims, which occurred under the Thaksin government.

The ICG says the government needs to address rising communal tensions by using Buddhist-Muslim security teams. It also recommends allowing schools to teach in the local Patani Malay.