The Sri Lankan health ministry says that a calculation error and the difficulty of identifying victims is the main reason for incorrect estimates of the total death toll. Sri Lanka has revised the death toll from last Sunday’s wave of bombings by more than 100, to “about 253”, the health ministry says. Sri Lankan authorities have blamed a local extremist group, National Towheed Jamaat. The “so called” Islamic State group has also claimed responsibility, though officials are still investigating the extent of any involvement but they haven’t ruled out outside help. Suicide bombers struck hotels and churches in Colombo, Negombo and the eastern city of Batticaloa on Easter . Most of those killed were Sri Lankan but dozens of foreigners were also among the casualties.