Police in Sri Lanka have arrested their top commander and a former defence chief over their alleged failures to prevent the Easter Sunday terror attacks. Hundreds of people were killed when churches and luxury hotels were hit by suicide bombers on Easter Sunday. It comes after advance warnings from intelligence services in India that attacks were being planned were ignored. Spokesman Ruwan Gunasekera said that Inspector-General Pujith Jayasundara and former defence secretary Hemasiri Fernando had been arrested on Tuesday. It comes a day after the attorney general said their failure to heed security warnings amounted to a crime against humanity. On Monday, Attorney General Dappula de Livera, wrote to the acting police chief urging him to bring charges against them. "There is sufficient information to prove negligence of official duties … and criminal negligence. It is also considered a grave crime against humanity under international law," he wrote. For lesser charges of negligence leading to damage of property, the two officials could face up to 52 years in prison. Sri Lankan President Maithripala Sirisena has accused the men of failing to act on an April 4 intelligence report about an attack planned for April 21, Easter Sunday. Jayasundara and Fernando have denied all allegations. More than 500 people were injured and 258 died in the atrocity. A state of emergency remains in Sri Lanka. The president had pledged to lift it last month but has now extended it on grounds of "public security". Just over 100 people, including 10 women, are in custody in connection with the suicide attacks against three churches and three luxury hotels in Colombo. A local militant organisation and ISIS claimed responsibility for the deadly attacks.