Media controlled by rebellious northern Ethiopian forces said the government launched air strikes on the capital of Tigray region on Monday, though the government denied the reports.
Tigrai TV, controlled by the northern region's Tigrayan People's Liberation Front (TPLF), said the attack on the city of Mekelle killed several civilians. An aid worker and a doctor in the region also said there had been a attack on the city.
Ethiopia's government spokesman, Legesse Tulu, denied launching any attack. "Why would the Ethiopian government attack its own city? Mekelle is an Ethiopian city," he said.
Reuters was unable to verify any of the accounts independently in an area that is off-limits to journalists.
Conflict erupted between forces loyal to the TPLF and the Ethiopian central government last November.
Tigrayan forces were initially beaten back, but recaptured most of the region in July and pushed into the neighboring Amhara and Afar regions, displacing hundreds of thousands more.
The TPLF, Tigray's former ruling party, says the government began a new offensive this month, though that has not been confirmed by the government.
Diplomats are worried that renewed fighting will further destabilize Ethiopia, a nation of 109 million people, and deepen hunger in Tigray and the surrounding regions.