"Five soldiers were also wounded from the fighting," he said.
The air raid targeted a gathering of senior rebels near their de facto capital of Kilinochchi, the military added.
The Tamil Tigers, who are fighting for a separate state in the island's north and east, were not immediately available for comment.
The military has captured large swathes of territory from the LTTE in the east of the country and is seeking to overrun their northern stronghold.
The LTTE has been blamed for recent bus bombings and suicide attacks, which have increasingly targeted civilians.
Thousands have reportedly been killed in recent months but analysts say both the government and the LTTE tend to exaggerate enemy losses as independent verification is not possible.
Sri Lanka's civil war has killed an estimated 70,000 people since 1983.