The BBC's Orlando de Guzman has made a second visit to the site of Wednesday's incident, in the northern village of Mapa Mamplam, and has been told by witnesses that boys, one as young as 12, were among the victims.

Military chiefs have denied the allegations, saying that civilians are never targeted.

Indonesian warships have been shelling rebel positions, as the military continues its offensive against the Free Aceh Movement (GAM), which began on Monday after peace talks broke down.

The villagers at Mapa Mamplam said a group of seven boys and men, aged between 12 and 20, were sleeping in a hut near a prawn farm to guard it – standard practice in rural areas.

A group of Indonesian soldiers entered the hut and dragged the boys out, lining them up on one of the dykes dividing the ponds, they said. A witness, who had a clear view of the events, told our correspondent that some of the group were then shot one by one at close range. Three or four others were then told to run, before being shot in the back, the villager said. In his first visit to the village, our correspondent saw four bodies with bullet wounds to the back of the head.

The military said on Friday it had killed 38 rebels since Monday. Rebels said 12 of their fighters had been killed, along with 53 civilians. Human rights workers say almost 10,000 people have fled their homes since the fighting started.

Major-General Endang Suwarya, the commander overseeing Indonesia's campaign in the strife-torn province, hass insisted: "Absolutely no civilians were killed. We have a list of targets that we want killed or captured. We don't miss or make mistakes." However, Foreign Minister Hassan Wirayuda admitted that rebels no longer wear military uniform, and therefore are difficult to distinguish from the local population.

Our correspondent says that whenever reports of such abuses come to light in Aceh, the GAM rebels and Indonesia's authorities tend to blame each other. However, he adds that in recent days there have been many confirmed cases of Indonesian troops storming into villages, dragging people out of their homes and brutalising them.

'All-out attack'

The BBC's Rachel Harvey says the army is determined to crush the rebels, amid evidence that supplies of food and fuel are running low in many areas.

So far, the offensive has largely taken the form of sporadic skirmishes, largely in the middle of the night, and mostly in the northern districts of Bireun and Pidie.

The military crackdown in Aceh began after talks with rebel negotiators broke down, ending a five-month-old peace deal that had raised hopes of a permanent resolution to the 26-year conflict. Indonesian President Megawati Sukarnoputri has imposed martial law, giving the military sweeping powers to make arrests, impose curfews and curb travel.

Acehnese resentment against Jakarta's rule has been fuelled by past abuses by the Indonesian military, and a feeling that the government is exploiting the region's resources.

The failed peace deal, signed in December, offered Aceh an autonomous government by 2004, which would have been allowed to keep 70% of the revenue generated from the province's rich oil reserves.

Military forces in Aceh

• GAM fighters: 5,000
• Indonesian troops: 28,000
• Indonesian regular police: 8,000
• Indonesian paramilitary police: 2,000