Ethiopian running legend Haile Gebrselassie has told the BBC that fake news shared on Facebook was behind violence in which 78 people died.
Trouble was sparked when an influential activist from the Oromo ethnic group, Jawar Mohammed said the authorities were endangering his life by removing his bodyguards.
The violence had ethnic and religious elements, the government said.
Gebrselassie said he could sue Facebook if they fail to remove certain posts.
The double Olympic champion was not explicit about which posts he was referring to, but told the BBC in the capital Addis Ababa that "fake news is easy to spread".
Referring to the death toll, the 46-year-old added that "the main cause I believe was Facebook".
I know my people, they don't do such awful things"
Days of violence in Ethiopia's Oromia region, which saw some people sheltering in churches, followed the accusations made on Facebook by Mr Jawar.
The police initially denied that it put his life in danger, but Prime Minister Abiy Ahmed later indicated that the police had acted incorrectly.
Graphic images, purporting to show the results of the trouble, began to circulate on social media.
Gebrselassie said he thought the pictures were not of Ethiopians. "I know my people, they don't do such awful things," he said.
'Ethiopia should be careful'
Some fake videos had been shared, including one of a claim that a local official was arming young men, the BBC's Kalkidan Yibeltal in Addis Ababa says.
Despite calls by the Nobel Peace Prize winning prime minister for unity, ethnic tensions are threatening to spill out of control.
Gebrselassie, who is now a successful businessman, warned that Ethiopia has "to be careful" saying that the genocide in Rwanda was not that long ago.
He also mentioned the conflicts in Libya, Syria and Yemen as examples of what could happen if things get out of hand.
The authorities have arrested more than 400 people in connection with October's violence and the trouble has subsided.
Facebook has not responded to Gebrselassie's accusations, but the company has a policy of "working to fight the spread of false news".