Doctors Without Borders says the United Nations Mission in South Sudan failed to protect civilians during a February attack on a base, where at least 25 people were killed.

The humanitarian group, also known as Medecins Sans Frontiers, released a report Tuesday detailing the failures of peacekeeping and humanitarian assistance during the attack in which two MSF staff members died.

MSF's report found that despite a strong military presence at the base in Malakal, the U.N. mission failed to prevent weapons from entering a camp holding displaced persons and chose not to intervene when fighting initially broke out.

A U.N. investigation blamed the attack on a "fragile and potentially explosive situation in the Upper Nile," and called for more resources so that peacekeepers can better protect civilians.