COLOMBO (Reuters) - The cornered Tamil Tigers on Sunday accused Sri Lanka of killing hundreds in an artillery barrage, which the military said the guerrillas had fired off themselves to win sympathy for a truce to stave off defeat. The reported attack is the latest in a series of accusations and counter-accusations about who is harming civilians, tens of thousands of whom are trapped inside the less than 5 square km of battlefield left in Asias longest modern war. The Liberation Tigers of Tamil Eelam (LTTE), surrounded by 50,000 soldiers and on the verge of conventional defeat, increasingly have urged external intervention to aid civilians - which the United Nations say they are holding as a human shield. The pro-rebel web site, www.TamilNet.com, said at least 257 bodies had been found and 814 people were wounded after an artillery barrage that began overnight and ended early on Sunday, quoting medical sources it did not identify. More than 2,000 innocent civilians have been killed in the last 24 hours. The wholesale bombardment ... on a densely populated, non-combatant civilian safe zone is state terrorism and a war crime, TamilNet quoted Selvarajah Pathma-nathan, the Tigers international diplomatic pointman, as saying. Brigadier Udaya Nanayakkara, the military spokesman, said troops had not fired into the area and had long ago stopped using heavy weapons in an effort to avoid civilian deaths. The radars detected the LTTE positioning their mortars south of the safe zone and firing from there. This morning, the radar detected two occasions of the LTTE firing to the safe zone to blame the military, he said.