Tigray's current president, or chief executive as he is also known in English, is Debretsion Gebremichael.
But he and other representatives of the TPLF regional party are accused by the Addis Ababa government of treason, armed insurgency and terrorism.
Ethiopian Prime Minister Abiy Ahmed also tried to stop the elections held in Tigray in September, which Debretsion won.
Instead, Abiy Ahmed appoints a new leader for Tigray, 52-year-old Mulu Nega.
He will "recruit and appoint leaders of regional bodies from the political parties that legally operate in the area," Abiy Ahmed wrote on Friday on Twitter.
The information channels from Tigray are restricted, but many dead, injured and fleeing are reported from the battles that have raged between the government and TPLF side since last week.
UN human rights chief Michelle Bachelet warns that violence could spread and affect both Eritrea and fragile Somalia.
Following reports of massacres, she points out that acts of war against civilians are war crimes.
"A protracted conflict will cause catastrophic damage to both Tigray and all of Ethiopia, nullifying years of development and progress," Bachelet wrote.