Sri Lanka's Tamil Tigers have used suicide bombers to hold back government forces who are close to overrunning the last patch of territory held by the rebels, the military said on Thursday.
The Tigers have deployed hundreds of suicide bombers to devastating effect in the past 20 years, claiming several high-profile victims including the then president Ranasinghe Premadasa in 1993.
Military spokesman Brigadier Udaya Nanayakkara said advancing ground troops had been confronted by suicide attacks, but gave no details on whether there had been any casualties.
The government estimates that up to 20,000 people are being held in the less than five-square-kilometre (two-square-mile) area where the rebels are holed up. The United Nations has said the number could be as high as 50,000.
President Mahinda Rajapakse, under pressure over allegations that his troops have been shelling civilians, on Wednesday invited UN Secretary General Ban Ki-moon to visit the island.
A UN document circulated among diplomats in Colombo last month said as many as 6,500 civilians may have been killed and another 14,000 wounded in the government's offensive this year, according to figures that were not verified.