The Ethiopian government and and the rebel Tigray People's Liberation Front (TPLF) agreed on Wednesday to cease hostilities, a dramatic diplomatic breakthrough two years into a war that has killed thousands, displaced millions and left hundreds of thousands facing famine.

Delegates from both sides signed the agreement in the South African capital Pretoria, just over a week after formal peace talks mediated by the African Union began there.

"The two parties in the Ethiopian conflict have formally agreed to the cessation of hostilities as well as to systematic, orderly, smooth and coordinated disarmament," said Olusegun Obasanjo, head of the African Union mediation team, at a ceremony.

Obasanjo, a former Nigerian president, said the agreement also included "restoration of law and order, restoration of services, unhindered access to humanitarian supplies, protection of civilians, especially women, children and other vulnerable groups".

An agreement had not been expected so soon. Earlier on Wednesday, the African Union had invited media to what it described as a briefing by Obasanjo. It was only when the event began, about three hours behind schedule, that it became clear a truce was about to be signed.

"This moment is not the end of the peace process. Implementation of the peace agreement signed today is critical for its success," said Obasanjo, adding that this would be supervised and monitored by a high-level African Union panel.

Ethiopian government representative Redwan Hussien, who is Prime Minister Abiy Ahmed's National Security Adviser, said all parties should be true to the letter and spirit of the agreement.

In response, Tigray delegate Getachew Reda, a spokesman for the regional authorities, spoke of the wide scale death and destruction in the region and said it was his hope and expectation that both parties would honour their commitments.

(With input from Reuters)