At least 22 people died and more than 100 were wounded when Ethiopian security forces fired into crowds on Wednesday in a third day of unrest over last month's disputed elections, medics and witnesses said.
Ethiopian authorities said police and troops opened fire on stone-throwing crowds who were looting shops, robbing banks, attacking police and trying to free detainees in custody.
The government blamed the main opposition Coalition for Unity and Democracy (CUD) for inciting the worst violence seen in Addis Ababa in four years.
"The government regrets very much," the loss of life, Information Minister Bereket Simon told Reuters. "CUD, which is the perpetrator of the violence, will have to take responsibility."
The CUD said the protests were spontaneous actions from the people which it had not orchestrated.
The shootings followed two days of student protests and weeks of rising tensions over preliminary results from May 15 parliamentary elections, which the CUD says were rigged by Prime Minister Meles Zenawi's ruling party, the Ethiopian People's Revolutionary Democratic Front (EPRDF).