Ban stressed that any systematic attack on the civilian population, due to their ethnic background, religious beliefs or faith may constitute a crime against humanity, adding that those responsible must be held accountable.
Moon said any systematic attack on the civilian population a crime
All armed groups must abide by international humanitarian law and protect civilians living in areas they control, Ban said. He added that the UN will continue to help meet the urgent humanitarian needs of those displaced by the conflict and the terrorist threat in Iraq.
Hundreds of Christian families and individuals fled their homes in the militant-seized city of Mosul, some 400 km north of Baghdad, by Saturday afternoon, a deadline declared earlier by the IS militant group for the minority to convert to Islam, leave the city, pay tax or die.
IS, formerly ISIS, is not formally recognised as a state and viewed as a rebel group. It is composed of Sunni insurgent groups and was thought to have significant ties to Al Qaeda. But the latter formally dissociated itself from IS in February.