Updated

A bomb planted in a dirt road killed six soldiers in southern Thailand on Monday, police said, in what apparently was an attack by Muslim separatists in an insurgency that has cost more than 6,500 lives since 2004.

Police Maj. Pompetch Chotiklang said the explosion in Pattani province also wounded four other soldiers and blew the truck they were traveling in into pieces, with parts of it landing 100 meters (yards) away.

The deaths were among the worst in a single incident suffered in recent years by the military in the south, said Srisompob Jitipiromsri, director of the independent research group Deep South Watch.

Four years ago, eight soldiers died when their truck was blown up by a bomb in Yala province. In April this year, six paramilitary rangers were shot and killed when their vehicle was blown off the road by a bomb in Narathiwat province.

Soldiers, police, civil servants and even civilians — including children and Muslims — have been the targets of the insurgents, a disparate group with nebulous leadership. Roadside bombs and drive-by shootings are their most common methods of attack. Recent talks between the government and the insurgents' representatives have made little progress, in part because of disagreement over who actually speaks for the separatist forces.

The insurgents are mostly active in Thailand's three southernmost provinces of Pattani, Narathiwat and Yala, the only ones with Muslim majorities in the Buddhist-dominated country. They are able to draw on the resentment of Muslims who feel they are treated as second-class citizens, as well as anger over the heavy-handed repression of the Muslim community by security forces seeking to clamp down on the insurgency.

Police say there is usually an upsurge in attacks during the Muslim holy month of Ramadan, which this year began on May 26 and ends on June 24.

On Saturday in Pattani, two attackers fatally shot two teenagers before making a getaway on motorbikes.

In another attack last Friday, four attackers on motorbikes fatally shot a policeman outside a police station in Narathiwat.