The victim, a resident of the district of Kilinochchi working for the UK-based HALO Trust, was clearing mines in Muhamalai in Jaffna when the explosion took place.
Between 2002 and October 2012, HALO Sri Lanka had cleared over 650 hectares (1,607 acres) of minefields and systematic Battle Area Clearance of over 1,640 hectares (4,052 acres) whilst destroying over 143,000 landmines, 51,500 items of large calibre ammunition and 440,000 bullets.
HALO's de-mining teams work alongside Sri Lankan Army's de-mining teams in battle zones of the island's brutal three-decade long civil war that claimed nearly 100,000 lives.
FSD, another de-mining organisation from Switzerland last week said their work has been hampered by cutting of financial contributions by international donors.
More than 5,000 square kilometres of land in the north and east was suspected to be heavily mined by the LTTE during the conflict.
Less than five per cent of the area remains to be cleared of mines, the army said in February this year.