NEW YORK — Ethiopia and Eritrea will attend a summit in Saudi Arabia on Sunday to sign an agreement cementing the thaw between the two former Horn of Africa enemies, a UN spokesman said on Friday.

Custodian of the Two Holy Mosques King Salman will host the signing ceremony in Jeddah to be attended by UN Secretary-General Antonio Guterres and African Union Commission chairman Moussa Faki Mahamat.

UN spokesman Farhan Haq did not provide details, saying the Ethiopian and Eritrean leaders would sign a “further agreement helping to cement the positive relations between them.”

On Tuesday, the leaders of Ethiopia and Eritrea reopened two land border crossing points for the first time in 20 years, clearing the way for trade between the two nations.

Ethiopia’s Prime Minister Abiy Ahmed and Eritreas President Isaias Afwerki signed a declaration of peace in July that formally ended two decades of hostility.

Eritrea gained its independence from Ethiopia in the early 1990s, and war broke out later that decade over a border dispute.

A 2002 UN-backed boundary demarcation was meant to settle the dispute for good, but Ethiopia refused to abide by it.

A turnaround began in June when Abiy announced that Ethiopia would hand back to Eritrea the disputed areas including the flashpoint town of Badme where the first shots of the border war were fired. — AFP