Thousands of people have fled villages in Sudan's South Kordofan region amid an assault by Sudanese forces. They say the army has launched a deliberate campaign to bomb and starve civilians in the disputed region where it is fighting rebels aligned with South Sudan. Almost every day, villages are hit by bombs, rockets and artillery. Many are sheltering in caves, and food is running scarce. The UN estimates about 300,000 people in the Nuba Mountains might starve if they do not get help. Al Jazeera's Peter Greste travelled to the remote region for this exclusive report.