A suspected Tamil Tiger suicide bomber on a motorbike blew himself up on Monday near a police building in a northern Sri Lankan town, killing 12 police officers and wounding 23 other people.The bomber struck police officers and civilian bystanders on a street in the northern town of Vavuniya, 210 km north of Colombo, military spokesman Brig. Udaya Nanayakkara said. Of the 23 wounded, 19 were police and the rest civilians, he said.Nanayakkara blamed the Tamil Tiger rebels for the attack. Rebel spokesman Rasiah Ilanthirayan could not be reached immediately for comment. Monday’s attack came after a weekend of heavy fighting as Sri Lanka’s air force destroyed a Tamil Tiger rebel base in the north,and 32 insurgents and seven soldiers were killed in sporadic ground fighting over two days, the military said.Ilanthirayan said Saturday’s airstrikes hit a civilian area, killing two people, but he denied any rebels had died in the fighting. It was not possible to verify the conflicting claims because reporters are not allowed into the northern war zone. Both sides routinely release contradictory reports on the war, exaggerating the damage on the opposing side while playing down their own losses.