Hundreds fleeing S.Sudan shooting seek U.N. refuge
Protest began after bodies of Dinka tribesmen found
Sudan, South Sudan to discuss rebel support next month
Sudan accuses Juba of supporting SPLM-North rebels
Number of aid workers attacked hits record in 2011
Most attacks on aid workers in 2011 took place in a handful of highly insecure countries, and kidnapping became the most frequent form of violence, a new report shows