Sri Lankan troops killed six Tamil Tiger fighters in two separate attacks and launched an airstrike on a northern rebel area, the military said. Meanwhile, the rebels said they attacked a bus carrying navy personnel Thursday, killing six in their second attack in a week in the country's normally peaceful south, but the navy denied the attack took place. Separately, army artillery fire killed three civilians in the north, the rebels said. The two sides routinely exaggerate their enemies' death tolls while downplaying their own casualty figures. It was not possible to independent confirmation the casualties.