Ethiopia’s Tigray forces fired rockets into the city of Bahir Dar in the Amhara region on Friday but caused no damage, the regional government said.
The Tigray fighters similarly hit Eritrea a few days ago.
The conflict in northern Ethiopia has killed hundreds over the past two weeks and sent 33,000 refugees into Sudan.
It has also called into question whether Prime Minister Abiy Ahmed – Africa’s youngest leader and last year’s Nobel Peace Prize winner – can hold his ethnically divided nation together.
The northern-based Tigray People’s Liberation Front (TPLF) effectively ruled Ethiopia for decades as the strongest force in a multi-ethnic coalition, until Abiy took power two years ago.
“The illegal TPLF group have launched a rocket attack around 1:40 a.m. in Bahir Dar,” the regional government’s communications office said on its Facebook page.
“The rockets have caused no damage.”
Amhara state has sent troops into Tigray in support of Abiy.
Ethiopia said on Thursday it was closing in on Mekelle, the capital of Tigray region.
Africa’s second most populous nation of 115 million people, Ethiopia is a federation of 10 states run by separate ethnic groups.
The latest war has pitted the central government against one of the most heavily militarised regions