COLOMBO (AFP) - Sri Lanka's military has demolished a fortified underground bunker used by Tamil Tiger supremo Velupillai Prabhakaran, who was killed in a final offensive four years ago, an official said on Friday.

Security forces set off a blast on Thursday that collapsed the complex as part of a wider operation to clear possible landmines and remove the "ghosts of terrorists", military spokesman brigadier Ruwan Wanigasooriya said.

"We don't want any ghosts of the terrorists," he stated.

Wanigasooriya said the well-fortified underground structure, 50m deep, was removed along with similar structures in the former war zone at Puthukkudiriruppu, where Prabhakaran was killed in a final battle in May 2009.

He said more than 100 bunkers of the Liberation Tigers of Tamil Eelam (LTTE) as well as the security forces had been dismantled following the end of nearly four decades of war.

Prabhakaran's bunker had become a key tourist attraction. The military had placed guides to explain strategic locations and facilities captured from the Tigers, who were known for their suicide bombings.

Sri Lanka's military has denied allegations from rights groups that up to 40,000 civilians were killed in the final months of fighting. The UN estimates that at least 100,000 people were killed between 1972 and May 2009.