COLOMBO: The Sri Lankan government vowed today to capture all Tamil Tiger-held territory within 48 hours, despite international calls for a truce and accounts of a “humanitarian catastrophe.” The signal that a final push against the beleaguered separatist guerrillas was in full swing came as United Nations Secretary General Ban Ki-moon’s chief of staff was rushing to the island in a fresh effort to stop the carnage.

The International Committee of the Red Cross (ICRC), the only neutral organisation working in the conflict area, said its staff were “witnessing an unimaginable humanitarian catastrophe.” Former colonial power Britain said it wanted an investigation into alleged war crimes, while the United States announced it was blocking a two-billion-dollar International Monetary Fund bailout package for Sri Lanka.

Tens of thousands of Tamil civilians are believed to be trapped inside a tiny patch of jungle on the northeast coast still held by the rebels.

Hundreds have been reported killed in indiscriminate shelling over the past week, adding to the thousands left dead since the rebels were pushed into a corner at the start of the year. Sri Lankan government spokesman Anusha Palpita said the war against the remaining rebels would be over by Sunday morning.

“The president (Mahinda Rajapakse) assured that within the next 48 hours the thousands of Tamil civilians will be freed from the clutches of the Tamil Tigers,” Palpita said. “All territory will be freed from Tiger control.” “We are closing in from all directions,” military spokesman Brigadier Udaya Nanayakkara added. The pro-rebel Tamilnet.com said the rebel zone was being heavily shelled, with close-quarter battles also raging.

State media showed footage of fires sweeping through the tropical beach and lagoon battle zone, and said the guerrillas appeared to be retreating and destroying ammunition stock piles. Sri Lanka’s ITN channel said some civilians were managing to escape. A fleeing Tamil woman told the channel that “there are people dead everywhere, on the streets and everywhere.” The government maintains that the Tigers are using civilians as human shields and they need to be rescued. Any civilian deaths inside Tiger territory have been blamed on the rebels. The UN’s human rights chief Navi Pillay, however, has said both sides may be guilty of war crimes.