At least six people, including children, were killed when the Ethiopian Air Force bombarded the Tigray region's capital Mekelle on Thursday, witnesses said.
Residents and hospital sources said more than 27 others were injured in the air raid.
Tigray rebels spokesman Getachew Reda said this was the sixth airstrike on the populous city.
"Another airstrike was carried out in Mekelle. Our air defense units are currently engaging enemy jets," he said.
Thursday's airstrikes targeted Mesfin Industrial Engineering, located in the centre of the regional capital. It was the second time the site was bombed since the military launched airstrikes last week.
The federal government says the Tigray People’s Liberation Front (TPLF) has turned the industrial facility into a weapons manufacturing and repair plant.
Following Thursday's air raid, TPLF has once again accused the government of targeting civilians.
But Addis Ababa has repeatedly rejected the accusation. The government said it only bombed military targets, including arms construction and repair sites and weapons caches in Mekelle.
At least nine people have died and over 50 injured since the Ethiopian military launched the aerial strikes on October 18.
Fighting between the federal government and TPLF first erupted in November last year.
But the conflict has intensified since October 11, when the Ethiopian army launched what it said was a "final and decisive offensive" against the TPLF, once a dominant part of the former ruling party.
The air raids are part of Ethiopia's major offensives to quell TPLF, a rebel group that is fighting government and allied forces in the Tigray, Amhara and Afar regions.
The United States government last week condemned Ethiopia for the escalation of violence after the military launched deadly air strikes in Mekelle. US officials urged warring factions to immediately cease hostilities and engage in peace talks.
The US had previously threatened to impose sanctions if the parties in the Tigray conflict failed to reach a negotiated settlement to end the nearly one-year bloody civil war.
The war has killed thousands and displaced millions.
About 5.2 million people, nearly 90 per cent of the Tigray population, need emergency assistance.
Hundreds of thousands are also living under famine-like conditions.