(Bloomberg) — United Nations security teams evaluating the situation in Ethiopia’s Tigray region have observed troops wearing Eritrean uniforms moving in the area, according to people familiar with the matter.

The observations follow claims by Tigrayan leaders that they’ve been battling Eritrean soldiers inside their territory since clashes between Ethiopian government forces and Tigrayan fighters erupted last month. The presence of Eritrean troops would suggest the conflict, which the Ethiopian government has characterized a domestic issue, has gone international.