Ethiopia on Tuesday called on "all able-bodied Ethiopians of age" to join the armed forces as the nine-month conflict in Tigray has spread in recent weeks to two neighbouring regions in the north of the country.
"It is now time for all able-bodied Ethiopians to join the defence forces, special forces and militias and show their patriotism," said a statement from Prime Minister Abiy Ahmed's office, which declared a unilateral ceasefire less than two months ago.
The conflict in Tigray has seen a dramatic turnaround since late June.
The fighting began last November after the Tigray region forces attacked and killed federal soldiers.
In late June, Abiy Ahmed declared a cease-fire which was rejected by the rebels. They continued their offensive into the neighbouring regions of Amhara in the south and Afar in the east.
Fighting there has displaced an estimated 300,000 people.
The United Nations said Tuesday it had regained access to two camps housing Eritrean refugees in Tigray. It warned that people living there were facing dire conditions.
UNHCR, the UN Refugee Agency, said that since July 13, violent clashes in the northern region had prevented their staff from reaching the Mai Aini and Adi Harush camps.
Some 23,000 Eritrean refugees in total live in the two camps.
Aid deliveries resumed on August 5, UNHCR spokesman Boris Cheshirkov told reporters in Geneva.
"However, access is limited by a complex and fluid security situation and refugees continue to face dire conditions," he said.
Eritrean and rebel forces have been accused of attacks on refugees.