The U.S. embassy in Ethiopia has authorized the voluntary departure of non-emergency government staff and family members because of armed conflict, it said on its website, as rebel forces in the north make advances.
The decision came after the United States said on Wednesday it was "gravely concerned" about the escalating violence and expansion of hostilities, repeating a call for a halt to military operations in favor of ceasefire talks.
"The (State) Department authorized the voluntary departure of non-emergency U.S. government employees and family members of emergency and non-emergency employees from Ethiopia due to armed conflict, civil unrest, and possible supply shortages," the embassy said in a statement.
Travel to Ethiopia is unsafe and further escalation is likely, it added.
"The government of Ethiopia has previously restricted or shut down internet, cellular data, and phone services during and after civil unrest," it said.
Government spokesperson Legesse Tulu did not immediately respond to a telephone call seeking comment on the U.S. embassy statement.
On Tuesday, Ethiopia declared a state of emergency, with forces from the northern region of Tigray threatening to advance on the capital, Addis Ababa.
Jeffrey Feltman, the U.S. special envoy for the Horn of Africa, is expected to arrive in Addis Ababa to press for a halt to military operations in the north and to seek the start of ceasefire talks.
On Wednesday, Britain urged its citizens to review their need to stay in Ethiopia and consider leaving while commercial options were available.
Prime Minister Abiy Ahmed pledged to bury his government's enemies "with our blood" as rebellious Tigrayan forces and their Oromo allies threaten to advance on Addis Ababa.
Abiy was awarded the Nobel Peace Prize in 2019 for settling Ethiopia's longtime conflict with Eritrea.
An earlier call to "bury" the enemy in a statement posted on Abiy's official Facebook page over the weekend was removed by the platform for violating its policies against inciting and supporting violence, the company said.
Tigrayan forces are in the town of Kemise in Amhara state, 325 km (200 miles) from the capital, a spokesman for the Tigray People's Liberation Front (TPLF), Getachew Reda, told Reuters late on Wednesday, pledging to minimize casualties in their drive to take Addis Ababa.
"We don't intend to shoot at civilians and we don't want bloodshed. If possible we would like the process to be peaceful."
A regional analyst in touch with the parties to the war and who spoke on condition of anonymity said the TPLF was likely to hold off on any advance on Addis Ababa until they secured the highway running from neighboring Djibouti to the capital.
That requires seizing the town of Mille. Getachew said on Tuesday that Tigrayan forces were closing in on Mille.