Ethiopia's Tigray rebels have agreed to a "cessation of hostilities" in their 16-month war with Addis Ababa, AFP reported on Friday, a day after the Ethiopian government declared a unilateral truce to allow aid into the embattled region.

It remains unclear how the two sides will enforce the ceasefire.

United Nations Secretary-General Antonio Guterres "hopes that this truce will translate into an effective cessation of hostilities, respected by all parties in this conflict, to allow for effective humanitarian access for all who need it," a UN spokesperson said in a statement on Thursday.

The conflict has left tens of thousands of civilians dead and sent the Tigray region into an acute humanitarian crisis. Over 90 percent of the 5.5 million Tigrayans are in need of food aid, according to the United Nations.