By Anbarasan Ethirajan
BBC News, Colombo
Aid agencies fear a humanitarian disaster in the north-east
The UN says that it estimates that thousands of civilians have been killed and wounded in the conflict in the north-east of Sri Lanka.
The UN's US-based Office for the Coordination of Humanitarian Affairs (OCHA) says civilians continue to lose their lives within the war zone.
It says that they are also being killed in the no-fire area which has been hit by artillery attacks.
The government says the UN's figures are "irresponsible and sensationalist".
But UN Secretary-General Ban Ki-moon has strongly deplored the mounting civilian death toll - which he said included children - and appealed to both the army and Tamil Tiger rebels to suspend hostilities to allow time for civilians to safely leave the conflict zone.
"The world body has no verifiable numbers due to lack of access for relief workers, but estimates that thousands have been killed and wounded," the UN News Centre said.
"The (government-designated) no-fire zone is believed to be very squalid and overcrowded and the UN has received information that people are dying from lack of food.
"The conditions there could lead to outbreaks of malaria, dengue fever and measles, and a chicken pox outbreak has already been reported."
It is the first time in the current round of conflict that the UN has talked about thousands of civilian casualties.
But the Sri Lankan foreign secretary Palitha Kohona told the BBC that it was irresponsible to make statements of this nature when the OCHA admitted that it had no access to the area.
India's previous official involvement in Sri Lanka proved disastrous
It is estimated that between 70,000 and 200,000 civilians are caught up in the conflict in the north-east.
Meanwhile India has announced that it is to send a medical team to aid north-eastern Sri Lanka's conflict zone, providing humanitarian relief and emergency care to displaced civilians.
It is the first time there has been an Indian presence at the war zone since a peacekeeping mission pulled out of Sri Lanka in 1990.
India says that the team will arrive on 9 March.
The medical team will consist of eight physicians and surgeons as well as paramedic and technical staff.
Correspondents say India's three-year peacekeeping mission to the island is widely regarded to be disaster, coming to an end with the loss of about 1,200 Indian troops.
The government said on Thursday that it was planning to open two new safe routes in the north-east for civilians to leave the conflict zone.
The Tigers have not yet reacted to the government's announcement and there is scepticism over the plan.