Coordinated Easter Sunday bombings at churches and hotels in Sri Lanka bore the hallmarks of militant groups Islamic State or al Qaeda, security experts said on Monday, citing the level of sophistication of the attacks. Rohan Gunaratna, a Singapore-based security expert, said the Sri Lankan group was the Islamic State branch in Sri Lanka and perpetrators were known to have links to Sri Lankans who travelled to the Middle East to join the hardline group in Syria and Iraq.