The federal government's policy of shipping off visa overstayers and people who failed the strict new character tests to Christmas Island led to a surge in immigration detainees on Christmas Island in the months leading up to last week's riot in the detention centre.

Immigration Minister Peter Dutton has estimated that rioters damaged up to $10 million in property in the Christmas Island detention centre after a two-day stand-off between Serco, the Australian Federal Police and detainees. According to asylum seeker advocates, the death of an Iranian asylum seeker who had escaped the detention centre triggered the riot. According to the Department of Immigration and Border Protection, the "disturbance" was caused by a minority of detainees who were in the centre for overstaying their visas or whose visas had been cancelled on character grounds.