Events in South Sudan, where hundreds have died in four days of fierce fighting between forces loyal to the country's rival leaders, are "totally unacceptable", African Union Commission president Nkosazana Dlamini-Zuma said Wednesday.

What is happening again in South Soudan is totally inacceptable," she said on opening AU talks in Rwanda's capital Kigali. "Governments and leadership are there to protect the vulnerable, to serve the people, not to be the cause of their suffering."