The violence broke out near the town of Lhokseumawe after protesters took to the streets following military operations against separatism in the province.

Local officials put the toll at 27 dead and up to 117 wounded. Local Red Cross officials launched a search alongside a government team for more victims of the shooting.

Indonesian armed forces chief General Wiranto said: "We really regret what happened in Aceh."

He said the military was investigating the shootings and would release an official report after the investigation.

Tom Butler reports: Hospitals were inundated with dead and injured

However the army said that only 18 people had been killed and 81 injured when troops opened fire in self-defence after protesters started stoning them.

This death toll was disputed by TS Sani, from the district authorities' fact-finding team.

He said: "A total of 19 people died at or were brought dead to hospitals and eight more (died) who had been taken home almost immediately after the clash."

He said 98 people had been wounded, while the Red Cross said there were 117 wounded in hospital.

The Commission for Disappearances and Victims of Violence, citing reports and witnesses, said the death toll might be as high as 65, although its members had only seen 23 bodies.

Missing soldier

The clash was reportedly triggered by an army search for a missing colleague whom they say had gone missing after he was caught by villagers during a rally in support of the Aceh Merdeka (Free Aceh) separatist movement on Saturday.

Doctors struggled to cope with the casualties from Monday's violence

Villagers had accused the soldier of infiltrating the rally while the army said he was visiting a relative.

A large crowd of villagers gathered and a stand-off ensued.

The army said thousands of villagers, armed with guns, spears and machetes attacked a battalion headquarters outside Lhokseumawe. It said the villagers were killed when soldiers shot at the crowd to try and regain control.

However Aceh Merdeka insists there was no provocation.

Lhokseumawe has seen several mass protests over the last month, mostly in support of a self-determination referendum for Aceh.

Three people were killed last month when soldiers shot into a crowd of some 10,000 protesters.

Free elections

Catherine Napier reports: Many people in Aceh won't bother to vote at all

Aceh Merdeka has been fighting for an Islamic state in the province since the 1970s.

The violence comes ahead of national elections in June - Indonesia's first free polls in more than four decades.

Former Jakarta Correspondent Catherine Napier says that it now looks as if many people in Aceh will not bother to vote at all.