The government and Tigray rebels have traded blame for initiating a military escalation that ended a five-month ceasefire.
Four people have been killed in an air strike on Tigray's capital city, a hospital official has said, with the government denying targeting civilians in the rebel-held region.
"Four are dead by the time they arrive (at) the hospital. Two of the dead are children," Kibrom Gebreselassie, chief clinical director at Mekele's Ayder Referral Hospital, told AFP news agency in a message on Friday.
The government said its air force was "targeting only military sites" in Tigray, dismissing claims that an air strike had struck a residential neighbourhood in regional capital Mekele.
The Tigray People's Liberation Front (TPLF) rebel group "has begun dumping fake body bags in civilian areas in order to claim that the air force attacked civilians," the government said in a statement.
Footage of collapsed buildings and medical personnel attending to injured people in Mekele were broadcast on Tigray TV, the broadcaster of the TPLF, which has been engaged in an armed conflict with the government since November 2020.
The incident came a day after both sides declared that a five-month ceasefire had been broken.
The government and rebels have traded blame for initiating a military escalation along the administrative border between the Amhara and Tigray state that ended the truce.
An earlier statement issued by the Government Communication Service said Ethiopian forces would conduct surgical operations targeting military training centres and arms depots in Tigray.
The government has expressed readiness to engage in talks with the rebels in the past several months without any pre-conditions as long as they are held under the sole mediation of the African Union.
But the Tigray rebels rejected the African Union as a mediator, recommending that talks be held with Kenyan outgoing President Uhuru Kenyatta acting as a mediator.
Thousands, mostly civilians, have been killed and millions displaced since the conflict began, with the UN blaming both sides for the deaths.
The UN has warned that Tigray "stands on the edge of a humanitarian disaster," with more than 40% of the region's estimated 6 million people in need of emergency assistance.
It also said that more than 5 million people were internally displaced in Afar and Amhara regional states where Tigrayan forces made military incursions a year ago, inflicting huge humanitarian and property damage.