Sri Lanka's military has launched air strikes on territory controlled by the Tamil Tiger rebels, following a land mine attack on a passenger bus that left at least 64 people dead and some 80 wounded.
Military sources say Sri Lanka's fighter jets attacked rebel targets near the eastern town of Mullativu.
A government spokesman, Keheliya Rambukwella blamed the rebels for the "barbaric attack" northeast of the capital, Colombo. It was the deadliest attack since a 2002 ceasefire.
The main Tamil rebel group denied responsibility and condemned the attack, which a spokesman said was aimed at discrediting the movement.
Washington called the death of 64 innocent civilians in Sri Lanka a terrorist attack and called for an end to violence. State Department spokesman Sean McCormack said the attack bears all the hallmarks of the Tamil Tiger rebels and is in clear violation of the cease-fire agreement that the rebels claim to uphold.