Intense fighting is being reported in Ethiopia's Amhara state - the latest sign that the war that erupted in the Tigray region in November is spreading.
An Amhara official told the BBC that federal forces as well as Amhara regional troops were involved in fighting Tigray rebels on three fronts.
This is despite the government saying a unilateral ceasefire declared last month had not been suspended.
All sides have accused each other of escalating the conflict.
The situation has intensified since Tigray People's Liberation Front rebels recaptured much of Tigray in a spectacular offensive against the national army in June.
Authorities around the country have been mobilising to join the fight, with rallies being held nationwide to encourage people to enlist.