A senior Tigray People’s Liberation Front commander in Ethiopia says TPLF forces have scored what he described as a major victory in the neighbouring Afar region.
He told the BBC that the rebels were also fighting troops allied to the federal government in southern and western Tigray, with three to four divisions engaged on every front.
The claim has not been independently confirmed.
At least 20 civilians have been killed and 54,000 people have been displaced in Afar, reports say, as fears grow of a fast-developing humanitarian crisis.
Eritrean refugees in southern Tigray spoke of heavy fighting in the area.
Regional forces from across Ethiopia are being deployed to Tigray following significant rebel advances in recent weeks.