A group of 150 Russians were behind the majority of violence in Marseille before the Euro 2016 match between England and Russia, French prosecutors have said.
Brice Robin, the chief prosecutor in Marseille, said 20 people had been arrested and 10 people, including six Britons, faced an immediate trial. A 16-year-old Briton was among those arrested, charged for throwing bottles.
At least 35 people were injured in the clashes, including four who were said to be in a serious condition.
Mr Robin told a press conference in Marseille that 150 "hyper-rapid and hyper-violent" Russians arrived by train.
He said: "These are extremely well trained people."
Russian fans were seen carrying equipment for assaults, including gum shields, fighting equipment and mixed martial arts gloves. Two Russian nationals have been expelled from the country.
The majority of the 35 people injured during the fighting were English, according to Mr Robin.
Mr Robin said one an Englishman, who had received blows to the head with an iron bar, is still in critical but "stable" condition. He suffered concussion and brain hemorrhage.
Alcohol has now been banned from “sensitive areas” around Euro 2016 matches after violence marred the opening days of the tournament.
