BBC News with Iain Purdon.

President Obama has led commemorations in New Orleans of the fifth anniversary of Hurricane Katrina, the storm that devastated the city and killed 1,800 people. Addressing students at Xavier University which has been rebuilt since the hurricane, Mr Obama said the disaster had been both natural and man-made.

"We all remember it keenly - water pouring through broken levees; mothers holding their children above the waterline; people stranded on rooftops begging for help; and bodies lying in the streets of a great American city. It was a natural disaster but also a man-made catastrophe; a shameful breakdown in government that left countless men and women and children abandoned and alone."