A growing number of children have been killed or injured in Sri Lankan fighting over the last 10 days, the UN children's agency Unicef says.
It has called on the government and Tamil Tiger rebels to give "absolute priority" to the safety of children and the wider civilian population.
The news agency, CNN, says children as young as 4 months old are being treated for shrapnel injuries and other "wounds of war."
Unicef Regional Director for South Asia Daniel Toole said "it is crucial that safe areas, schools and medical facilities are protected and considered zones of peace, in all circumstances."
He said "children are bearing the brunt of a conflict which is not theirs. We are gravely concerned for the tens of thousands of children who are trapped in a fast shrinking area of intense conflict."
But Sri Lanka's defence secretary Gotabaya Rajapakse said the numbers were exaggerated and aid agencies were panicking.
The UN on Thursday evacuated 350 wounded civilians, including 50 children, after negotiations with the Tigers, who have been accused of holding 250,000 civilians hostage in an area they still hold.
Sri Lanka's government on Friday rejected international calls for a ceasefire and said the military is in its final phase of operations to defeat the Tamil separatists after 37 years of unrest.