The reports of a fresh offensive come despite mounting international criticism of the brutal near 11-month conflict in the north of the country.
Ethiopian troops and their allies are waging air and ground offensives against Tigray rebels in the northern region of Amhara, humanitarian sources have said.
The military strikes took place in several areas of Amhara on Thursday and Friday, the sources said, amid growing speculation of a major push by government forces against the rebels.
The reports come just days after Prime Minister Abiy Ahmed was sworn in for a new term on Monday, vowing to stand strong and defend "Ethiopia's honour" despite mounting international criticism of the brutal near 11-month conflict i n the north of the country.
The war in northern Ethiopia erupted in November when Abiy sent troops into Tigray to topple the regional ruling party, the Tigray People's Liberation Front, a move he said came in response to TPLF attacks on federal army camps.
Although government forces quickly took control of Tigray's cities and towns, the TPLF recaptured most of the region including the capital Mekele by late June.
Fighting has since spread to the neighbouring Amhara and Afar regions, and triggered what the United Nations has called an "immense humanitarian crisis" with hundreds of thousands of people driven into famine-like conditions.
An untold number of civilians have been killed, nearly two million have been displaced, and there have been many reports of atrocities including massacres and mass rape.
UN chief Antonio Guterres, who has said more than five million people were in need of humanitarian assistance, on Wednesday urged the Ethiopian authorities to allow t he UN to deliver aid "without hindrance".