Two people were killed and 21 injured in a riot at Korydallos prison in Athens, Greece, the Justice Ministry said Sunday, according to Agence France-Presse. Initial reports indicate the riot broke out after the prisoners were served dinner as inmates attacked each other with makeshift knives.

The violence stemmed from a conflict between rival Albanian and Pakistani gangs held in the facility’s C Wing, but the reason for the fighting was unclear. Eight people were said to be seriously injured. Several ambulances were seen outside the prison, AFP reported.

International human rights groups have previously expressed concern over inhumane treatment of detainees and overcrowding at Korydallos. Amnesty International has consistently cited the prison as having some of the worst conditions of any European prison. 

In February 2014, some Korydallos prisoners took part in a hunger strike to protest what they said were the prison's appalling living conditions. Detainees reported being forced to beg for medical care and media reports discovered the prison’s hospital was 140 people over capacity. Many of the prisoners suffered from such contagious diseases as HIV, tuberculosis and hepatitis. 

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