The International Committee of the Red Cross (ICRC) says that the number of civilians killed and injured in Sri Lanka has reached "appalling levels".
The ICRC says many of the victims are schoolchildren
New figures released by the organisation show that 180 civilians died in the first six weeks of 2008, and nearly 270 more were injured.
In one bombing, more than half the members of a school baseball team died.
Violence on the island has increased since the government formally withdrew from a 2002 ceasefire last month.
"Sadly, many of the victims have been children on their way to or from school," ICRC delegation head Toon Vandenhove said in a statement.
Violence has increased since the ceasefire ended
Fighting has been intensive around Tamil Tiger controlled areas in the north - with the government accusing the rebels of retaliating against their offensive with attacks against civilian and military targets in the south.
A series of skirmishes on Wednesday in the northern Mannar and Vavuniya districts killed 15 Tamil Tiger rebels, the defence ministry said.
Correspondents say that the casualty figures provided by both sides are usually impossible to verify and each tends to downplay its own losses while exaggerating those of the other.
The rebels have been fighting since 1983 for an independent homeland for Tamils, who they say have been discriminated against by successive Sri Lankan governments.
Correspondents say that fighting between the two sides since then has killed more than 70,000 people.
More than 1,000 people have been killed since the government withdrew from the ceasefire, according to the military.