COLOMBO, Sri Lanka - More than 15,000 civilians have fled Sri Lanka's northern war zone over the last three days, an official said Sunday, as government forces appeared poised to crush the separatist Tamil Tigers.
Meanwhile, attacks in the north killed at least 21 rebels over the weekend, according to the military.
The military's relentless offensive in recent months has almost routed the rebels, virtually ending their 25-year war for a separate Tamil nation in the Sinhalese-majority country.
But the United Nations and aid agencies have expressed concern for the estimated 250,000 civilians trapped in the shrinking sliver of land still controlled by the Tigers. International organizations including the Red Cross have urged both sides to let the noncombatants out of the conflict zone.
"So far on Sunday, 4,600 civilians have come to the government areas," military spokesman Brig. Udaya Nanayakkara said.
He said 5,600 fled the war zone on Saturday while another 5,000 crossed over Friday, bringing the total for the three days to 15,200.
The government accuses the rebels of holding civilians as human shields, a charge the rebels deny.
The Red Cross said Saturday that some 400 patients are also stranded in a makeshift hospital in the north. It urged both sides to allow them to be evacuated.
Warnings from the United Nations on Friday of a looming food crisis in the conflict zone added to the plight of civilians trapped in the region. The group said that the World Food Program stocks in the area were gone.
Sri Lanka barred nearly all aid groups from the war zone last year. It does also not allow in journalists, making independent verification of the situation impossible.
Heavy fighting continued Sunday, with the navy destroying two rebel boats 16 kilometers off the northeastern coast, killing at least six insurgents, navy spokesman Capt. D.K.P Dassanayake said.
On Saturday, army troops foiled a rebel attempt to breach the government forces' defense line near the town of Puthukkudiyiruppu in the north, killing at least 15 insurgents, a military statement said.
Separately, air force jets bombed a series of rebel positions Saturday, including an artillery gun, the military said.
The rebels could not be reached for comment because communications to rebel-held territory have been severed.
Some 70,000 people have died in Sri Lanka's civil war, which began in 1983 after years of marginalization of Tamils by governments dominated by the Sinhalese majority.
