Ethiopian Prime Minister Abiy Ahmed on Wednesday vowed to repel attacks after rebels in the disputed northern region of Tigray launched a fresh offensive.
"We will defend and repel these attacks by our internal and external enemies, while working to speed up humanitarian efforts," Abiy said in a statement posted on Twitter.
Tigrayan forces this week renewed their assault in the conflict-hit northern region, claiming a series of battlefield gains two weeks after the federal government declared a unilateral ceasefire in the face of rebel advances.
The latest rebel push followed the recapture of the regional capital Mekele last month from federal forces, a turning point in a brutal eight-month conflict that has killed thousands of people and left many hundreds of thousands facing famine.
Abiy, the Nobel Prize laureate whose decision to go to war in Tigray damaged his reputation as a peacemaker, said his government remained committed to a cessation of hostilities even if it comes at a "cost".
"We've undertaken a unilateral ceasefire to avoid further conflict, to provide the people with a reprieve during the farming season, and to allow aid operations to proceed without excuse," he said.
UN calls for Eritrean withdrawal
Abiy sent troops into Tigray last November after accusing the region's once-dominant ruling party of orchestrating attacks on Ethiopian military bases.
Those enemies were "unable to rest without conflict", he said.
"Our people should, as they have shown before, act in unison as one army to ensure the country's survival, support the Ethiopian National Defence Forces, and defend and repel outside pressure and internal provocation," he said.
The conflict has been marked by massacres and sexual violence, and the involvement of Eritrean and regional forces fighting alongside Ethiopia's national army.
The UN Human Rights Council on Tuesday called for an immediate end to all violations in Tigray and the quick and verifiable withdrawal of Eritrean troops from the battle-scarred region.