Sri Lanka's top defence ministry official quit Thursday, taking responsibility for security failures that led to suicide bombings that killed nearly 360 people, a ministry official said.

Hemasiri Fernando, the most senior bureaucrat at the ministry, sent a letter of resignation to President Maithripala Sirisena, the official said.

"He told the president that he was accepting responsibility and resigning so that the president can make a new appointment," the official said, speaking on condition of anonymity.