Sri Lanka's air force bombed and destroyed a Tamil Tiger rebel base in the country's embattled north on Saturday, while infantry clashes in the same region killed 31 rebels and four soldiers, the military said. In the latest assault, air force fighter jets pounded a Tamil Tiger supply base and an intelligence operation center deep in rebel-held Mullaitivu district early Saturday, said air force spokesman Wing Commander Janaka Nanayakkara. He said the airstrikes were successful and had destroyed the base. Separately, helicopter gunships overnight hit a radio center operated by the Sea Tigers, the rebels' naval wing, in their stronghold of Kilinochchi, he was quoted as saying by the Associated Press.