JAKARTA - Residents of Indonesia’s eastern region of Poso geared up for the biggest holiday on the Islamic calendar as police sought clues to the beheadings of three teenage Christian girls by mysterious assailants.

Police said they had questioned six people about the attacks on the students but had yet to identify leads into the killings, which have again highlighted simmering tension in Poso regency, racked for years by sectarian violence.

Most of the communal violence in the large but sparsely populated Poso area occurs around the predominantly Muslim seaside town of Poso and the hilltop Christian town of Tentena.

National police spokesman Aryanto Budihardjo said one student who survived the attack was among the six witnesses under questioning.

"I cannot conclude whether the perpetrators come from outside of Poso. The brutal actions against these school children indicate attempts to conduct terror before Eid al-Fitr," he said, referring to the Muslim holiday that marks the end of the holy month of Ramadan and falls on Thursday this year.

Police had previously said that up to six people dressed in black outfits and masks carried out the attack with machetes.

With only a few days before the festival, more residents in Poso, about 1500km northeast of the capital Jakarta, flocked to markets and shops despite a heavy police presence.

"Markets are open as usual and they are rather crowded because Eid al-Fitr is coming soon," a police official, Iskandar Adam, told Reuters by telephone from Poso which is located on the eastern island of Sulawesi.

"It is relatively safe here in Poso. Everything is normal," Adam added.

More than 1000 police have been deployed to secure the rugged Central Sulawesi regency of Poso.

The murders have been widely condemned, including from the Vatican, which described them as "barbaric".

Muslim-Christian clashes in the Poso regency killed around 2000 people from 1998 through 2001, when a truce was struck.

While the worst violence abated after the peace deal, there have been sporadic outbreaks since, including market bombings last May in Tentena that killed 22 people.

The three headless bodies of the girls, dressed in brown uniforms, were left at the site of the attack. Their heads were found at separate locations two hours later by residents.

About 85 percent of Indonesia’s 220 million people are Muslim. But in some eastern parts, Christian and Muslim populations are about equal.

Most Indonesian Muslims are moderates, but there has been an increasingly active militant minority in recent years.

- REUTERS