Regional forces and aid workers have reported heavy shelling in the rebellious northern region, with the Tigray People's Liberation Front saying the Ethiopian military has launched an offensive to capture Mekelle.
The northern Ethiopian city of Mekelle came under "heavy bombardment" by Ethiopian forces on Saturday, Debretsion Gebremichael, leader of the Tigray People's Liberation Front (TPLF), told Reuters news agency.
Gebremichael said the Ethiopian government forces had begun an offensive to capture the regional capital.
Ethiopia's military "has started hitting with heavy weaponry and artillery the center of Mekelle," the local government said in a statement carried by Tigrayan media.
Two humanitarian officials in the city confirmed these reports, according to AFP news agency.
Reuters cited a diplomat in direct contact with residents as saying that explosions were reported in the north of the city, in the Hamidai area. A second diplomat also said the attack had begun.
Ethiopian Prime Minister Abiy Ahmed's office announced Saturday that government security forces had captured the city of Adigrat and was advancing on Mekele, the capital of the northern Tigray region.
Last Sunday, the Ethiopian government gave the TPLF an ultimatum - which expired on Wednesday - to lay down arms or face an assault on Mekelle, a city of 500,000 people.
The Tigray region has been facing a rebellion since earlier this month. On November 4, security forces loyal to the TPLF attacked the Northern Command of the Ethiopian National Defense Force (ENDF) in Mekele, killing several people.
While the TPLF claimed the strike was carried out in "self-defense," Abiy said the TPLF had "crossed a red line" and ordered a military offensive.
Hundreds, possibly thousands, have died in the past weeks, and more than 30,000 refugees have fled to Sudan. The conflict has also spread beyond Tigray, whose forces have fired rockets at the neighboring Amhara region and Eritrea.
On Saturday, TPLF leader Debretsion accused the Eritrean military of crossing the border and raiding refugee camps in Tigray to capture refugees who have fled Eritrea in the past.
Tigrayans, who make up about 6% of Ethiopia's 115 million population, dominated the government until Abiy took power two years ago.
The African Union (AU) has designated a special envoy to mediate between the government and the TPLF, which is also the region's ruling political party.
Abiy, who won last year's Nobel Peace Prize for a peace deal with neighboring Eritrea, has said he wants to remove the TPLF leaders before negotiations. He has also appointed an alternative interim government to run Tigray.
The TPLF is popular in the Tigray region and dominated national politics until 1991.
Abiy's office said Friday that the central government is committed to the "protection and security of civilians" in the northern Tigray region where federal troops are battling regional forces.
Billene Seyoum, a spokeswoman for the prime minister's office, also said that Ethiopian forces would not "bombard" civilian areas, adding "the safety of Ethiopians in Mekelle and Tigray region continues as priority for the federal government."
shs/aw (Reuters, AFP)