At least 140 people have been killed in Ethiopia over the past two months in a crackdown on anti-government protests sparked by plans to expand the capital into farmland
"Security forces have killed at least 140 protesters and injured many more, according to activists, in what may be the biggest crisis to hit Ethiopia since the 2005 election violence."
The United States, a key ally of Ethiopia, last month expressed "grave concern" over the unrest. Washington has also criticised Ethiopia's arrest of journalists following the crackdown.
"By treating both opposition politicians and peaceful protesters with an iron fist, the government is closing off ways for Ethiopians to nonviolently express legitimate grievances," Horne said.
"This is a dangerous trajectory that could put Ethiopia's long-term stability at risk."