The office of Ethiopian Prime Minister Abiy Ahmed on Tuesday urged "all capable Ethiopians" to join the army, special forces and militias to support the fight against Tigrayan forces.
The statement came roughly six weeks after the government declared a unilateral ceasefire in the northern region of Tigray.
It was not immediately possible to contact the spokesperson for Tigrayan forces, or Abiy's representative, for comment.
"Now is the right time for all capable Ethiopians who are of age to join the Defence Forces, Special Forces and militias to show your patriotism," the statement said.
War broke out in November between federal troops and forces from the Tigray People's Liberation Front, which ruled Ethiopia for three decades and now controls Tigray.
The government declared a unilateral ceasefire on June 28 after Tigrayan forces recaptured the regional capital Mekele from federal troops. It said the ceasefire was for humanitarian reasons and would stay in place until the farming season ended.
The main planting season ruins from June to September.
"It has become apparent that Tigrayan farmers will not be able to farm safely unless the people of Tigray are forever separated from the terrorist group," the prime minister's office said in its statement on Tuesday.
In recent weeks, fighting has spread to the adjoining Amhara and Afar regions, displacing around 170,000 people, according to the United Nations.
About 4 million people in Tigray, Amhara and Afar are facing emergency or crisis levels of food insecurity, according to the UN.