Sri Lanka's Tamil Tiger rebels have carried out an air raid on a major naval base at Trincomalee on the east of the island, military officials said.
One plane dropped two bombs on the dockyard, injuring four sailors, the military said.
It is the first such aerial attack in more than a year.
Government forces have been pushing into rebel-held territory in the north of the island. The Tamil rebels are fighting for a separate state.
Military spokesman Brigadier Udaya Nanayakkara said air force jets had been scrambled to intercept the plane, but witnesses of the attack said they thought the rebel plane had escaped.
The Tamil Tigers have their own tiny air force of a few light planes smuggled into rebel-held territory in pieces and then reassembled.