Ethiopian Prime Minister Abiy Ahmed has urged civilians to join the armed forces as fighting intensifies across the country.
"Now is the right time for all capable Ethiopians who are of age to join the Defence Forces, Special Forces and militias and show your patriotism," Mr Abiy's office said.
The call comes less than six weeks after the prime minister declared a unilateral ceasefire in the war against Tigrayan rebels in the north.
Ethiopian government troops entered the region in November last year to bring down ruling party the Tigray People's Liberation Front and promised a swift conclusion.
The TPLF had held elections without the blessing of the government, which has suspended all other polls due to the coronavirus.
The group declared a landslide victory.
Fighting has forced more than two million people from their homes, and more than 50,000 people have fled into neighbouring Sudan.
In June, the government declared a unilateral ceasefire amid heavy civilian casualties and a famine declared by the UN.
But on Tuesday, Mr Abiy appeared to have lost patience with the rebels, who continued to win back territory and even push into neighbouring regions.
He ordered security forces "to halt the destruction of the treasonous and terrorist TPLF organisation and the machinations of foreign hands once and for all".
"The TPLF's goal and purpose is to disintegrate Ethiopia," he said.
Survivors told hospital officials they had been shot by TPLF fighters, he said.
Two officials with Afar's regional government put the death toll in Galicoma at more than 200, but the figure could not be independently verified.
Ayish Yasin, head of Afar's bureau for women and children, told AFP that "200 bodies of civilians have been recovered so far, while more than 48 are still missing".
"Out of the 200 bodies recovered, 107 are children - 48 girls and 59 boys," she said.
The head of the UN children's agency, Henrietta Fore, said on Monday she was "extremely alarmed by the reported killings of over 200 people, including more than 100 children, in attacks on displaced families" in Afar.
A Unicef spokesman on Tuesday said it had received "credible information from partners" about the attacks and that various UN agencies were planning to assess the site "as soon as security permits".
Ethiopian officials have seized on the Galicoma deaths as proof of the TPLF's disregard for the worsening humanitarian situation in Tigray.
But TPLF spokesman Getachew Reda said on Twitter on Monday that government troops "launched an offensive on August 5 against our forces in Galicoma".
He said the TPLF would "work with relevant bodies to investigate any incident that may have occurred".
Aid agencies have warned of dire days ahead as humanitarian access remains hamstrung by security woes.
On Tuesday the UN refugee agency said it had regained access to two Eritrean refugee camps in Tigray for the first time since July 13.
Although aid deliveries resumed on August 5, UNHCR spokesman Boris Cheshirkov told reporters in Geneva that access to the camps, which house 23,000 people, remains "limited by a complex and fluid security situation".
"Basic services such as healthcare remain unavailable, and clean drinking water is running out," he added.