The area was under the control of the Tamil Tigers for over 20 years. The fall of Puthukudyiruppu was a significant milestone in the crushing defeat of the LTTE.
All top LTTE leaders, including its chief V Prabakaran, were residents as the Army advanced into the area in the final military battle in early 2009.
The finding comes close on the heels of the discovery of at least two mass graves, one in the northern district of Mannar and the other in the central district of Matale.
Sri Lanka is currently under the focus of the international community for alleged war crimes during the final battle with the LTTE.
The US plans to move a third Sri Lanka resolution this month at the UN Human Rights Council which is likely to call for an independent international probe.