Amid what the Sri Lankan government is calling the final days of a 25-year-old conflict, health officials are estimating that up to 300 civilians have been killed in the fighting over the last week in the northern part of the country.

A 25-year war of separation between Sri Lanka's Singhalese Buddhist-dominated government and the Hindu Tamil Tigers is believed to be close to an end.

Sri Lankan security forces have recaptured most of the territory it lost to the Tigers over the years by unleashing intense air and ground attacks.

Government forces captured Mullaittivu, the last town held by the rebels, on Sunday.

But a humanitarian crisis is now unfolding and aid agencies are struggling to get into the area, said Angela Hoyt, spokeswoman with the International Committee of the Red Cross.

"People are not being protected," Hoyt said. "They're being caught up in the crossfire. Ambulances have been hit with shelling, hospitals have been hit with shelling and the hospitals that are there are overwhelmed and ill-equipped to deal with it."

The Red Cross estimates 250,000 civilians have fled to the jungle where fighting is taking place.

Dr. Thurairajah Varatharajah, the top government health official in Mullaittivu district, told the Associated Press by telephone at least 1,140 civilians — about 248 younger than 15 — were wounded in the fighting and brought to three hospitals in the district.

The number killed was difficult to count because many civilians had stopped bringing dead relatives to the hospital amid the heavy fighting, he said.

"In my opinion, there are a lot of deaths. More than 250 to 300," he said, adding his estimate was based on reports from residents who came to the hospitals from the war zone.

The report came as the government pledged to refrain from launching attacks inside a civilian refuge area set up in the war zone.

Military spokesman Brig. Udaya Nanayakkara said no civilians had been killed in the fighting, though some who had been forced to build fortifications by the rebels — known formally as the Liberation Tigers of Tamil Eelam — might have been wounded in the crossfire.

"There were no civilians killed," he said. "We are targeting the LTTE. We are not targeting any civilians so there can't be any civilians killed."

But the United Nations reported Wednesday that dozens of its workers and their relatives have come under artillery fire believed to be from government troops.

The military denied firing into the area, which is a government declared safe zone, during its offensive to root the rebels from the northeast.

Nanayakkara said 3,141 civilians have fled to the government-controlled territory in January.

The Tamil Tigers have fought since 1983 to create a separate state for minority Tamils, who have suffered decades of marginalization at the hands of governments controlled by the Sinhalese majority.

More than 70,000 people have been killed in the civil war.

With files from the Associated Press