The African Union's special envoy to Ethiopia, Olusegun Obasanjo, has warned that dialogue cannot deliver peace to Ethiopia while the war continues to intensify.
Mr Obasanjo says he remained hopeful about possible talks but that all sides needed to stop fighting and find some common ground.
The Tigrayans say there can be no dialogue until the federal authorities allow aid into Tigray, where tens of thousands are on the brink of famine.
The government says the Tigrayans must recognise its legitimacy and withdraw from the regions of Amhara and Afar.