Rebel forces from Ethiopia's conflict-hit Tigray region have accused the African Union of bias, days after the bloc appointed the former Nigerian President Olusegun Obasanjo as a mediator.

A spokesman for the Tigray People's Liberation Front (TPLF), Getachew Reda, accused the AU of siding with the Ethiopian government and barely acknowledging the existence of the 10-month conflict.

On social media he said the TPLF was not against the appointment of a mediator but said it would be naive to expect the mission to work.

The Ethiopian government has repeatedly said it would not be willing to hold talks with the TPLF which it has described as a terrorist organisation.