Ethiopia's military claims it has seized control of several towns in the northern region of Tigray.
The army has been locked in conflict with the Tigray People's Liberation Front (TPLF) for weeks, reports BBC.Lieutenant-General Hassan Ibrahim said the army had captured Wikro, north of the Tigrayan capital Mekelle, along with several other towns.
Also on Saturday, the TPLF leader told Reuters in a text message that Mekelle was under "heavy bombardment".
Debretsion Gebremichael said that government forces had started an operation to capture the regional capital.
The government has not commented on the latest development, but it said on Friday it was beginning the "final phase" of an offensive in the region.
Hundreds of people have reportedly been killed and thousands have been forced from their homes as Ethiopian forces have seized towns.
Details of the fighting are hard to confirm because all phone, mobile and internet communications with the Tigray region have been cut.The Ethiopian military has previously said it intended to seize Mekelle within days, but would avoid harming the 500,000 civilians there.
According to Reuters, a spokeswoman for the prime minister said Ethiopian forces would not "bombard" civilian areas.
"The safety of Ethiopians in Mekelle and Tigray region continues as priority for the federal government," Billene Seyoum added.
In a meeting on Friday, Prime Minister Abiy Ahmed told African peace envoys that civilians in the region would be protected.
However, there was no mention of potential talks to bring the fighting to an end and the envoys were not allowed to visit Tigray.
The TPLF party, which controls Mekelle, has vowed to keep fighting.
The UN has warned of possible war crimes if the Ethiopian army attacks Mekelle.
The UN has also expressed concerns about the lack of access to the region for humanitarian workers.
The Ethiopian authorities on Thursday said that "a humanitarian access route" overseen by the government will be opened up, adding that they were "committed to work with UN agencies... to protect civilians and those who need it".
More than 40,000 people have fled Ethiopia since the conflict began.
On Thursday, Ethiopian troops were deployed along the Tigray region's border with Sudan, where they prevented people fleeing the violence from leaving the country, according to refugees.
The BBC's Anne Soy, on the Sudanese side of the border, saw at least a dozen members of the Ethiopian military, leading to a marked decrease in the number of people crossing into Sudan.
The TPLF fighters, drawn mostly from a paramilitary unit and a well-drilled local militia, are thought to number about 250,000. Some analysts fear that the situation could turn into a guerrilla conflict - with the TPLF continuing to mount attacks on government forces even if they take Mekelle.
Leader of the TPLF, Debretsion Gebremichael, has said Tigray forces are "ready to die in defence of our right to administer our region".
Reuters quoted a diplomatic source as saying the TPLF "have mobilised lots of people in Mekelle". The person added: "They are digging trenches and everyone has an AK-47 [rifle]."
Aid groups fear the conflict could trigger a humanitarian crisis and destabilise the Horn of Africa region.
Ethiopia's state-appointed Human Rights Commission has accused a Tigrayan youth group of being behind a massacre earlier this month in which it says more than 600 non-Tigrayan civilians in the town of Mai-Kadra were killed. The TPLF has denied involvement.
The conflict is rooted in longstanding tension between Ethiopia's central government and the TPLF, which was the dominant political force in the whole country until Mr Abiy came to power in 2018 and introduced a series of far-reaching reforms.
When Mr Abiy postponed a national election because of coronavirus in June, relations further deteriorated.
The TPLF said the central government's mandate to rule had expired, arguing that Mr Abiy had not been tested in a national election.
In September the party held its own election, which the central government said was "illegal".
Then, on 4 November, the Ethiopian prime minister announced an operation against the TPLF, accusing its forces of attacking the army's northern command headquarters in Mekelle.