"The Amhara regional special force, which was in a national mission along with the ENDF, has withdrawn from the area, as per the deal," the Ethiopian National Defence Force (ENDF) said in a statement late on Thursday.
Withdrawal of the Amhara forces is a key step toward implementing the truce, alongside the disarmament of Tigrayan forces, which began to hand over its heavy weapons on Wednesday.
Fighters from Amhara entered Tigray in November 2020 to support the army. They also captured a swathe of territory in western Tigray that they say was historically theirs.
It did not appear that the Amhara forces had withdrawn from the western territory. Experts worry that the long-running territorial dispute could derail prospects for a lasting peace.
Gizachew Muluneh, spokesperson for the Amhara regional administration, and Getachew Reda, spokesperson for the Tigrayan forces, did not immediately respond to requests for comment.
The restoration of basic services to Tigray, resumption of humanitarian aid and withdrawal of troops from neighboring Eritrea, who also fought alongside Ethiopia's army, are also central to the deal.
Ethiopia's federal government and the Tigray People's Liberation Front (TPLF), a guerrilla force-turned political party that dominates the region, agreed on Nov. 2 to stop fighting following talks.
Eritrean soldiers began to pull out of several major towns in Tigray late last month. However, they have not left those towns entirely, residents say, and it is not clear whether they intend to leave.
Eritrea, which was not a party to the truce, has declined to comment on whether its troops will leave Tigray.