Rights body Amnesty International has condemned recent arrests of thousands of people in Ethiopia's capital, Addis Ababa.

It said the detentions "threaten a new era of human rights gains" under Prime Minister Abiy Ahmed.

Ethiopian authorities say that police had conducted a wave of arrests in the wake of recent ethnic violence between Oromos and other minority groups that left dozens dead in the capital and its Burayu suburb.

News agency AFP reports, quoting a source, that 65 people had been killed in the violence.

A total of of 3,200 people have been arrested, state-affiliated Fana Broadcasting Corporate reported.

Addis Ababa police chief Degfie Bedi said around 1,200 people believed to be involved in the fighting were detained, with charges filed against 107 suspects.

A further 2,000 were arrested at casinos, shisha clubs and establishments where people chew the leafy khat narcotic stimulant, Fana said.

Mr Degfie said those found not to have taken part in the violence would be released after receiving "training".

Mr Abiy took power in April and has implemented several reforms including the freeing of dissidents and unbanning opposition groups including the Oromo Liberation Front (OLF), that were formerly labelled terrorist organisations.

Some of the exiled opposition leaders have been returning to Ethiopia.