Tomi Soetjipto, Jakarta – Indonesia's military said on Wednesday it would court-martial 27 soldiers accused of torturing to death civilians in the restive province of Aceh.

"There were 27 suspects and four witnesses. The suspects were from different forces in the Indonesian Armed Forces (ABRI), the witnesses were all police," Lhokseumawe military commander Johny Wahab told Reuters by telephone.

Military officials and human rights groups have said that last week troops attacked and tortured villagers who had been detained in a raid on an Acehnese village suspected of harbouring separatists. Four people were killed and 20 injured in the attack in the industrial town of Lhokseumawe on the northern tip of Sumatra, some 1,600 km (1,000 miles) northwest of Jakarta.

Armed forces chief General Wiranto said the incident would be thoroughly investigated and he expected a fair, open trial. "The brutal action by soldiers is upsetting the military. I hope the court would roll on as soon as possible in a fair and open process," Wiranto told reporters after a cabinet meeting.

The head of the armed forces in parliament, Lieutenant-General Hari Sabarno, said talk of a split within ABRI was unfounded. "The soldiers were acting outside the military command, therefore they were being undisciplined. The incident does not show a split within the military," he told Reuters.

Asked whether the incident was the result of conflict among senior officials in ABRI, Sabarno said: "No, I don't think there are conflicts of interest among the officers."

Indonesia's rupiah currency weakened on Wednesday partly on concern that the events in Aceh were a further sign the military was in danger of splitting apart.

On Wednesday Wiranto called on Indonesians not to spread rumours which could worsen the situation. "Do not turn the heat up. We must prevent this (conflict) turning into a political commodity for certain groups," he said.

Troops in the staunchly Moslem, resource-rich province are hunting an alleged separatist leader called Ahmad Kandang, whom they accuse of masterminding attacks on police and the military. The detainees who were attacked last week were netted in a raid on a village by troops searching for Kandang.

In late December a mob of machete-wielding villagers dragged off-duty soldiers off a public bus. Six were tortured and killed and two other soldiers are still missing. On January 3 civilians were killed when security forces and separatists exchanged gunfire during a protest by a mob which attacked government buildings near Lhokseumawe. Human rights groups say 17 died while the army puts the toll at 11.

The New York-based Human Right Watch said on Tuesday that the military must cease its operations in the province. "The cycle of violence will not be stopped by sending more troops with unlimited authority to search homes and unlimited powers of arrest," it said in a statement.

A separatist movement has been simmering for years in the province, fuelled by claims that Jakarta gives little in return for plundering the region's natural resources. Separatist protests have gained momentum in a number of parts of the Indonesian archipelago since the downfall of former President Suharto in May after a 32-autocratic rule during which any attempts to break away from Jakarta were swiftly crushed.