A leading Tamil Tiger leader Rasiah Ilanthriyan was believed to have been killed as Sri Lankan troops continued their march into the rapidly shrinking areas held by the rebels.

The offensive is bringing Army troops almost to a face-to-face confrontation with the Tiger top brass. But, the pace of advance appears to have been slowed down by heavy mining and fear of large-scale civilian casualties.

Illanthriyan, who was LTTE military spokesman was killed in a skirmish with the troops in Kariyamullivaikkal along with LTTE, Sea Tigers' deputy chief Cheliyan.

As the Army moved deeper into the shrinking rebel enclave in the 'Civilian Safety Zone' in the embattled north, it faced condemnation from UN which said that in two days of shelling at least 430 ethnic Tamil civilians were killed and thousands other injured terming it as a "bloodbath".

The pro-LTTE website Tamilnet had reported on Sunday that Ilanthirayan was seriously wounded in clashes. It said he was a senior cadre from Batticaloa and he had been in key positions in the LTTE.

But an army official said the security forces had no confirmation of Ilanthirayan's death, so far.

LTTE fighters have heavily minded the area obstructing the security forces' advance and continue mounting heavy mortars attacks from the guns positioned inside the "Civilian Safe Zone" itself, the official said.

Three bodies of LTTE rebels killed during the fighting were found in subsequent search operations. The Army also made a haul of large quantities of arms and ammunitions Kanchikudichchiaru area.

Troops operating in close proximity to the newly declared "Civilian Safe Zone (CSZ)" have further continued their ground advances to rescue the civilian hostages held by the LTTE rebels on Sunday, the ministry said.

Army's electronic monitoring devices have picked up rebel conversations which indicate that key leaders of the LTTE are now leading the battle.

The decisive battle is likely to confront Sri Lankan forces in Vellamullivaikkal area, where they believe that the LTTE supremo V Prabhakaran is holed up with his top aides.

With the reports of heavy civilian casualties, which Sri Lankan officials have strongly disputed as "LTTE misinformation", a leading human rights organisation have called for UN Security Council to intervene.

A pro-LTTE website Tamilnet blamed the artillery attacks on the government, while the military accused the beleaguered Tamil Tigers of shelling their own territories to gain international sympathy and force a ceasefire.

As conflicting reports emerge on civilian casualties, a military spokesman claimed that a fresh batch of more than 1500 civilians have crossed over to the government controlled areas on Sunday.