Ethiopia’s Foreign Ministry said Thursday that the embassy closure was a response to what it described as Eritrea’s "direct and indirect acts of hostility and belligerence” toward Ethiopia. The ministry also accused the expelled diplomats of engaging in activities that threatened Ethiopia’s national security and violated the Vienna Convention on Diplomatic Relations.

Among those ordered to leave Ethiopia within 48 hours were Eritrea’s chargé d’affaires and officials accredited to the African Union, according to the Ethiopian government.

Eritrea rejected the accusations, arguing that Ethiopia was responsible for worsening relations. In a statement issued Thursday, Asmara accused Ethiopia of seeking access to the Red Sea and supporting armed opposition groups operating against the Eritrean government.

Eritrea said it would respond by severing all diplomatic ties with Ethiopia, deepening an already serious dispute between the two neighboring countries.

The diplomatic fallout comes against the backdrop of broader tensions in the Horn of Africa involving Ethiopia, Eritrea and Egypt, with regional concerns growing over security, territorial interests and access to the Red Sea.

The African Union Commission said Thursday that it was closely monitoring the escalating tensions and urged all three countries to exercise maximum restraint. The continental body called on the governments to avoid actions or statements that could further aggravate the situation.

The AU also encouraged Ethiopia, Eritrea and Egypt to keep communication channels open and settle their differences through diplomacy and peaceful dialogue.

The commission said it was prepared, in consultation with the countries involved, to support efforts aimed at reducing tensions, promoting dialogue and finding a peaceful resolution to the disputes.