Excavators in Sri Lanka have found the skeletal remains of 21 children as well as signs of possible torture of the dead in the biggest mass grave in the country’s former civil war zone, Mannar, putting a spotlight on the island’s recent record of human rights violations.

So far 276 skeletons have been exhumed, with forensic archaeologist Professor Raj Somadeva saying the number already makes it the “largest mass grave ever explored on the island”.

“We have excavated only 70 per cent of the gravesite, so the body count is bound to be much higher,” Professor Somadeva told The Independent.

Metal objects that appear to bind together the legs of the dead have raised new questions about what happened to the victims in the mass grave.

Who they were – and who killed them – remains uncertain. However experts agree the presence of children shows this was “certainly a [whole] community of people”.

Sri Lanka’s humanitarian crisis Show all 15 1 /15 Sri Lanka’s humanitarian crisis Sri Lanka’s humanitarian crisis Sahira 34, her husband Ahm 38 and their 4 children at the foot of their plot. Their two room home is not big enough to raise a family. Paddy Dowling Sri Lanka’s humanitarian crisis Sahira 34, resident of Muththunagar resorts to to collecting mussels for 12 hours a day which she sells on the market for £2.50 which barely feeds her family of six. The work is exhausting and dangerous. Paddy Dowling Sri Lanka’s humanitarian crisis One of many buildings destroyed in Muttur during Sri Lanka’s 26 year civil war. Typically doors, windows and roofs were removed by soldiers on both sides to construct bunkers. Paddy Dowling Sri Lanka’s humanitarian crisis Sajeeda 23, single mother of two left to raise her children after her husband divorced her to re-marry in a neighbouring town whilst he was looking for work. Paddy Dowling Sri Lanka’s humanitarian crisis Nasmeeya 6, plays on their plot of land which is covered in blend of sand and burnt rice husks which make it black in appearance but helps the nutrients in the soil for growing vegetables. Paddy Dowling Sri Lanka’s humanitarian crisis Abdul Cadar 67, a recipient of a new home under the Muslim Aids ‘Housing scheme’ after he became to ill to work and provide any income from his family. Paddy Dowling Sri Lanka’s humanitarian crisis Hairunisa’s family living in Kulumeemakada are all beneficiaries of the Muslim Aid ‘Livelihoods’ programme designed to provide economic empowerment to rebuild their lives. Paddy Dowling Sri Lanka’s humanitarian crisis Farshana 46, works the tides collecting mussels to provide for her family. Paddy Dowling Sri Lanka’s humanitarian crisis Rafeek 55, is too tired to hold a conversation with me. He suffers from a deteriorating medical condition which he cannot afford to treat. Rafeek and his family had not eaten for 3 days. Paddy Dowling Sri Lanka’s humanitarian crisis Hairunisa 35, a widower, enrolled in the Muslim Aid Livelihoods programme now supports her mother and her children working from home buying fabric and making garments for local villagers in Kulumeemakada. Paddy Dowling Sri Lanka’s humanitarian crisis Hairunisa 35, working from home on her newly purchased industrial sewing machine making garments which she sells and carrys out alterations. Paddy Dowling Sri Lanka’s humanitarian crisis Amir Khan 80, living alone whilst his wife receives treatment and remains in hospital. He grows his own vegetables on his plot and has a few chickens which yields enough for him to live off. Paddy Dowling Sri Lanka’s humanitarian crisis Asmya 13, lives with her family in Shafi Nagar, Muttur. Her and the rest of her family have not eaten for 3 days as they have no money to buy food. They wait patiently for handouts from villagers. Paddy Dowling Sri Lanka’s humanitarian crisis Abdul 50, The 'Tailor of Mutur’. Wanted to provide a better education for his children so he received a micro finance loan to buy an industrial sewing machine and some fabric. With his loan repaid in full he has now increased his monthly income from £75 to £225. As his business expands he looks to create 6 new jobs. Paddy Dowling Sri Lanka’s humanitarian crisis Younis 56, a widower lives alone as her home was too small to accommodate her children and their families. She sells watermelon for 12 hours a day by the roadside in the relentless sun to earn herself £2 p/day. She dreams of having her own business wholesaling fabric. Pictures by Paddy Dowling

The excavation, which started in May when a construction worker stumbled upon a human bone, is still in its early stages according to the chief investigation officer of the Mannar mass grave, Dr Saminda Rajapakse.

“We still don’t know the exact period of these deaths,” he said. “We have no idea who the victims are, their names or whether they were Tamil civilians, rebels or Sinhalese soldiers. Nothing.”

Although pottery, porcelain, metal objects and some jewellery worn by the victims have been found at the gravesite, there are no signs of clothes.

While it is too early to hold responsible either the Sri Lankan military or the Tamil Tiger rebels, who fought a bloody civil war from 1983 to 2009, human rights activists and the families of missing people are already demanding justice.

P Nagamma, a 67-year-old Tamil woman, said she believed her 18-year-old son lies buried in the Mannar mass grave. She told The Independent he was arrested by the Sri Lankan military on suspicion of being a terrorist in the early Nineties.

“He had just gone out to meet a friend and eyewitnesses told me that some unknown men took him away near the site where they found the grave,” Ms Nagamma said tearfully. “I have been waiting for him for 27 years, somehow hoping he’ll be alive somewhere. But now I think he’s lying in that grave.”

Police tape closes off part of a mass grave where authorities found skeletal remains of over 150 people at the Matale hospital compound in central Sri Lanka (AFP/Getty)

Ms Nagamma was not alone in that belief. Sandrapradasham Niranchan, a lawyer fighting for the families of the disappeared, has filed affidavits on behalf of nine families stating their husbands or sons were taken into custody by the army, navy or unknown groups in Mannar and were among the victims in the mass grave.

“Torturing and killing civilians is a blatant human rights crime. There are children in that mass grave. And we are certain there are more of these gravesites around the country where the disappeared Tamils have been buried,” he said.

The mass grave in Mannar, a Tamil-majority area, was the scene of a number of battles during the war, in which more than 100,000 people died and at least 20,000 – mostly Tamils – remain missing.

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Rights groups allege both the military and the Tamil Tigers are to blame for civilian deaths and disappearances. However, former president Mahinda Rajapaksa, who faces international war crimes charges and was instrumental in ending the long drawn-out conflict, has maintained the Sri Lankan military caused not a single civilian casualty.

A spokesperson for the Sri Lankan military claimed it was not responsible for the grave. “The army is not involved in that gravesite. We had nothing to do with it,” brigadier Sumith Atapattu said.

The Tamil Tigers themselves committed many atrocities, ruthlessly executing soldiers, Tamil civilians who did not support them and sometimes their own guerrilla members. The terrorist group, which had sophisticated air, sea and land units is also accused of using civilians as human shields throughout the conflict.

“It is extremely possible that the LTTE (Tamil Tigers) could be responsible for the people in that grave,” Dr Paikiasothy Saravanamuttu, an ethnic Tamil human rights activist, told The Independent.