Brigadier Ruwan Wanigasooriya, the military spokesman said that in a former LTTE base in Udayarkattukulam a minor explosion had occurred during preparatory work for construction work there.
Preliminary investigations showed that a stock of detonators hidden by the LTTE had exploded when a soldier unknowingly dug the ground for some construction work, Wanigasooriya said.
Mullaithivu for decades remained the LTTE's military capital when they ran a parallel administration in the north and east.
Last month, after 4 years since the LTTE was defeated, the military said an underground bunker used by the late LTTE leader Velupillai Prabakaran had been discovered in Mullaithivu.