Ethiopian military has "completely captured" an airport in northwest town of Humera, close to border with Sudan and Eritrea, local media report.
Ethiopian troops have taken an airport in the restive Tigray region during an offensive against local leaders defying Prime Minister Abiy Ahmed's authority, as the African Union (AU) called for an end to the bloodshed.
"The Ethiopian National Defence Force has fully captured Humera Airport amid the continuation of government’s military response against TPLF rebel group (Tigray People's Liberation Front)," local Fana TV reported, referring to the group that leads the government in the Tigray region.
Humera is located in the far northwest of the country, near the borders with Sudan and Ethiopia.
Also on Tuesday, at least 30 armed Ethiopian troops and "large numbers" of refugees fleeing the fresh fighting crossed the border into Sudan, the state-run SUNA news agency reported, while one diplomat on Tuesday said hundreds of people have been reported killed on both sides of Ethiopia's week-long conflict.
The troops from Ethiopia's Amhara region neighbouring Tigray fled into Sudan's Qadarif province on Monday evening, the SUNA report said, citing witnesses.
Local authorities have started to prepare a refugee camp for the fleeing Ethiopians, it said, while aid groups warn of a brewing humanitarian crisis affecting millions of people at the heart of the Horn of Africa region.
The Ethiopian troops turned themselves and their weapons in, and appealed for protection as fighting raged over the border, said a Sudanese military official on condition of anonymity because he was not authorised to brief reporters.
With the region almost completely cut off, it remained difficult to confirm either side's claims.
Each blames the other for sparking the conflict.
"Around three thousand refugees crossed over," Alsir Khaled, head of Sudan's refugee agency in the border town of Kassala, told AFP news agency on Tuesday.
African Union responds to 'hostilities'
The African Union Commission chairman, Moussa Faki Mahamat, called for the "immediate cessation of hostilities."
In a statement on Monday, he said the AU, based in Ethiopia, is ready to support an "inter-Ethiopian effort in the pursuit of peace and stability."
Faki urged "the parties to engage in dialogue to seek a peaceful solution in the interests of the country" and said the 55-nation bloc was ready to support an Ethiopian-led effort to solving the crisis.
Nobel Peace Prize-winning PM Ahmed has vowed that his military will bring a speedy end to the fighting in the heavily armed Tigray region and the removal of its leadership, which his government regards as illegal.
Abiy has shown no sign of opening talks with the TPLF, which once dominated Ethiopia’s ruling coalition.
Abiy said operations against the TPLF were "proceeding as planned".
"Operations will cease as soon as the criminal junta is disarmed, legitimate administration in the region restored, and fugitives apprehended & brought to justice – all of them rapidly coming within reach," he posted on Twitter.
Feeling marginalised by Abiy's political reforms after he took office in 2018, it broke away last year as the prime minister sought to transform the coalition into a single Prosperity Party.
The TPLF defied the federal government by holding a local election in September.
Diplomats and others assert that the conflict in Tigray could destabilise the region and other parts of Ethiopia, Africa’s second-most populous country with 110 million people.
Ethiopia has scores of ethnic groups and other regions that have sought more autonomy even as Abiy tries to hold the country together with exhortations of national unity.
Several hundred killed
Several hundred people reportedly have been killed on both the Ethiopian government side and the Tigray regional government side, a diplomat in the capital, Addis Ababa, told The Associated Press.
Ethiopia's state television on Monday showed scenes of federal government troops arriving in the border town of Dansha, to cheers, and of what the report said were Tigrayan militia members after surrendering to federal forces.
More than 150 citizens of European Union countries alone are thought to be in the Tigray region, which is increasingly cut off with airports and roads closed and communications largely severed, and governments are trying to ensure their consular protection, the diplomat added, speaking on condition of anonymity.
"There are so many uncertainties," the diplomat said.
"How far can Abiy go with this operation while keeping the possibility of, in the end, having a more or less peaceful solution? You need the support of the people."
READ MORE: Is Ethiopia on the brink of civil war?
Risks with conflict escalation
Experts worry that the longer the conflict lasts, the more difficult it will be for the federal government to bring the Tigray region back to Ethiopia's federation of regional states.
And aid groups warn the humanitarian needs will grow.
A United Nations spokesman told reporters on Monday that discussions were underway on the relocation of all non-essential UN staff and on gaining humanitarian access.