Chris McCall, Jakarta – A top figure in Indonesia's unstable east yesterday called for the Government to crack down hard on religious bloodshed, as the military said at least 123 had been killed in the latest flashpoint area.

The military commander for Sulawesi said the death toll from two weeks of killing in Poso was provisional and represented only corpses actually found. The true figure could be far higher, Major-General Slamet Kirbiantoro said. Police in Poso said they were aware of only 69 deaths. Whatever the death toll, it is the worst violence on the huge island for years.

The killings have gone hand in hand with new attacks in the neighbouring Maluku Islands, where thousands have died in 17 months of sectarian conflict.

Poso community leaders insist the unrest is the work of provocateurs and needs tough and quick action to stop it setting off copycat violence elsewhere in the country.

"It will spread very fast. The Government needs to act very fast," prominent Muslim businessman and political heavyweight Des Alwi said. "It needs to send in more troops and more helicopters. They only respect modern, strong weapons."

Sources in Poso said the town was calm but tense yesterday. Thousands of people have fled the fighting – carried out, as elsewhere, largely with home-made weapons such as bows and arrows. Like many worst-hit areas in the Malukus, Poso has a roughly equal number of Christians and Muslims. A small coastal town, it was the site of small-scale religious clashes two years ago.

Local people say the tension, as in the Malukus, is due to the gradual influx of Muslims to what had once been a Christian-majority area, and to resentment about which side received government jobs.

Poso is now a virtual ghost town. "There are no people any more in Poso, only the security forces," said Mahenda Papasi, the head of the local Protestant Church synod. He was speaking from the neighbouring town of Tentena, a Christian area to the south now packed with Christian refugees.

Recent bloodshed in the Maluku islands of Ambon and Halmahera has been widely blamed on the arrival of a so-called Muslim "jihad force" whose members have vowed to fight a holy war against Christians. Analysts have been warning that just as the violence gradually spread throughout the Malukus, it could infect Sulawesi.

Mr Alwi, who is from the Banda islands, where all the Christians were forced at knifepoint to leave, said he and a friend had written to President Abdurrahman Wahid a few weeks ago to urge stern measures.

He warned it was now a deeply personal conflict for many of those involved. Many of those now coming to fight in the name of Allah had relatives killed on Halmahera in January, Mr Alwi said, in an attack by Christians in which his own nephew also died. "The families will come back for revenge," he said. "When there is fear, when they don't know if they are going to die or not, people are more mean."