in Ethiopia's Gambella regional state after the deaths of two aid workers there, a local U.N. official said Friday.

Steven Were Omamo, acting U.N. humanitarian coordinator to Ethiopia, told VOA's Horn of Africa service that aid operations would be on hold indefinitely until security in the region improved.

Action Against Hunger, a U.S.-based charity, reported that two of its staff members were killed early Thursday. They were in transit to the Nguenyyiel Refugee Camp in western Ethiopia when armed attackers ambushed their vehicle.

The victims' identities have not been released pending notification of their families. 

Omamo said his office was consulting with regional and federal Ethiopian officials about security measures.

Gambella and other parts of Ethiopia have seen an upsurge in ethnic violence and internal displacement in recent months. 

VOA