Violence in eastern Chad is preventing aid workers from reaching thousands of refugees who fled Sudanese government attacks in Darfur last week, with a new wave of refugees expected after fresh bombardments. Beatrice Godefroy, head of the Swiss branch of Doctors Without Borders in Chad, told Reuters up to 8,000 refugees had poured across the border from Darfur last week and were living rough in the desolate area around the border town of Birak.