Six months of war have plunged Sudan into one of the worst "humanitarian nightmares" in recent history, UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, Martin Griffiths, said on Sunday, calling on the warring parties to uphold their obligations under international humanitarian law, and urging donors to step up their support. He also highlighted the growing need for humanitarian assistance in neighboring countries, to which more than a million people have already fled.