Pressure is building on Sri Lanka and the Tamil Tiger rebels to protect thousands of civilians caught up in the fighting on the island.
UN Secretary General Ban Ki Moon has expressed deep concern over the fate of the civilians - the UN says dozens are dead or injured.
And the European Union has asked the government to ensure that the civilians are spared in the fighting.
Sri Lanka's army has pushed the rebels from their strongholds.
Mullaitivu, their last major base, fell on Sunday.
There is no way of confirming claims from either side in the conflict zone as independent journalists are barred.
Mr Ban said in a statement that he "is deeply concerned about the safety and well-being of civilians caught in intensified fighting in the Vanni region of Sri Lanka" between government troops and rebels.