Fighting has widened across northern Ethiopia, with the federal army saying it repelled attacks by Tigrayan forces and their allies as clashes spread around Tigray and into neighbouring Amhara and Afar.
The military's statement was its first since hostilities intensified on Wednesday, while Tigrayan officials accused federal forces of launching a major offensive involving infantry, mechanised units and drones.
The competing accounts could not be independently verified.
The Ethiopian army said fighting began in Amhara near the Tigray border and claimed its troops inflicted heavy casualties and captured weapons.
Tigrayan forces, meanwhile, said they had begun counteroffensive operations after federal attacks across several fronts.
Reports also indicated fighting in Afar, where a humanitarian source told AFP that Tigrayan forces used heavy artillery while attempting to seize Yallo.
Tigrayan forces also took control of three airports from federal police, including Mekelle's airport, prompting Ethiopian Airlines to suspend flights across Tigray.
Local reports said Tigrayan forces had also captured Abala in Afar.
Mekelle itself remained calm, according to a resident interviewed by the BBC, although movement was limited and residents were increasingly concerned about cash shortages and possible communications disruptions.
The escalation came days after the TPLF and six other armed movements announced the Ethiopian Peoples' Forces Alliance for Survival, committing themselves to removing Prime Minister Abiy Ahmed's government.
The coalition includes the Amhara Fano National Movement and Oromo Liberation Army, alongside movements linked to Somali, Afar and Benishangul-Gumuz areas.
Its formation follows political realignments after the 2022 Pretoria agreement ended the two-year Tigray war but was followed by growing disputes among former allies.
The alliance said federal forces were attacking its members on several fronts, while government officials have accused its members of prior collaboration and alleged backing from Eritrea.
Eritrea has repeatedly denied supporting Ethiopian armed groups.
IGAD has called for an end to hostilities and renewed direct dialogue, while the United Nations has expressed concern over the armed coalition and reported drone attacks.