COLOMBO, Sri Lanka (AP) -- Fighting between Sri Lankan government forces and rebels retreating to a small patch of jungle has trapped thousands of innocent people and killed "many" civilians, a senior U.N. official said Monday.
The military captured the rebels' final stronghold of Mullaittivu on Sunday and fought heavy battles with the separatists in a rapidly shrinking, densely populated war zone on Monday, the military said.
"There have been many civilians killed over the last two days," he said. "It's really a crisis now."
Buhne said that until recently both sides in the fighting worked hard to avoid civilian casualties.
"But in the current phase, with such a level of fighting and with so many people around, unless there is very, very close attention to it, it's almost inevitable," he said.
Human rights groups and diplomats have expressed growing concerns about the safety of the civilians in the north in recent days. Many have accused the Tamil Tigers of preventing civilians from fleeing the war zone, while the government has said the rebels hoped to use the civilians as human shields.
The government unilaterally declared a "safe zone" in a small section of rebel-held territory last week and called on all the civilians to move into that area, where they would be protected.
But there have been several reports of artillery fire in that region and Buhne said there was regular fighting in the "safe zone" in recent days.
"It's hard for us to assign responsibility, but there's definitely been fighting," he said.
The military has repeatedly denied fighting in that area.
"We are not targeting this safe zone," military spokesman Brig. Udaya Nanayakkara said. "(The rebels) have moved their weapons to the safe zone and are firing from the safe zone but we don't engage them."
Rebel officials could not be reached for comment because communications to the northern war zone have been cut. Independent accounts of the fighting are not available because most journalists are barred from the war zone.
The Tamil Tigers have fought since 1983 to create a separate state in the north and east for minority Tamils, who have suffered decades of marginalization at the hands of successive governments controlled by the Sinhalese majority. More than 70,000 people have been killed in the violence.
The government has vowed to crush the group and has squeezed the rebels into a 115-square-mile (300-square-kilometer) area in the jungle.
Troops were consolidating their control of Mullaittivu on Monday while other forces pushed into the jungles in the Vishwamadu area and fought pitched battles with the rebels there, Nanayakkara said.
"They are engaging with artillery. They are engaging with mortars. They are engaging with small arms," he said.
Reports of civilian casualties in the area have grown in recent weeks.
One diplomat said the use of heavy artillery in such a confined area so densely populated with civilians was extremely dangerous and could result in more civilian deaths than if the government relied solely on ground troops.
The diplomat spoke on condition of anonymity for fear of antagonizing the Sri Lankan government. International aid workers also refused to speak publicly, fearing the government will brand them rebel sympathizers and expel them.
Army commander Lt. Gen. Sarath Fonseka said Sunday the war was "95 percent," over but analysts warn that it is simply shifting from a conventional fight between two armies to a guerrilla war.