In their first public acknowledgement that government forces were moving deeper into areas previously held by them, the Tigers said civilians have had to move several times because of the military onslaught.
"Persistent shelling in this area, where two weeks ago a large number of internally displaced people sought refuge, forced them to (move) again further inside Kilinochchi," the Tigers said, referring to their political capital.
"Such multiple displacements are also adding to the delays in providing adequate shelter," the Tigers said in a statement.
The Sri Lankan government, which pulled out of a Norwegian-brokered ceasefire with the rebels in January, says its troops are advancing on several fronts in their bid to dismantle the Tamil Tigers' northern mini-state.
The Liberation Tigers of Tamil Eelam (LTTE), who have been fighting for a separate ethnic state since 1972, accused the military of shelling civilian settlements.
"Many of the internally displaced people, who