A group of up to 50 masked thugs attacked a bar packed with English football fans in Lyon on Wednesday night.
Tottenham Hotspur supporters were in the Smoking Dog pub before their team's game in the French city.
Witnesses said three Tottenham fans were taken to hospital, one with a head injury, and claimed the attack had an anti-Semitic motive.
The Foreign and Commonwealth Office (FCO) said it was aware of reports of an attack and was offering assistance.
Tottenham fans said the attackers, some making Nazi salutes, smashed doors and threw cast iron chairs, wooden objects, and a flare into the pub, where up to 150 supporters were drinking. They said the attack on the bar, which is popular among ex-pats, happened at 10.18pm. The thugs returned shortly afterwards to launch another assault on the pub, which was damaged extensively as a result.
Landlord, Dave Eales from Retford, Nottinghamshire, said: "At 10.18 the pub was rammed with Tottenham fans watching the Champions League on the television. The front of the pub, which is made up of reinforced glass, was attacked by 20-25 people. They threw projectiles through the windows. There was a stand off. They didn't get into the bar. Then it calmed down. Then they came back a second time and it all started again. There were three injured Tottenham fans taken away by ambulance. One of them had a head injury. I'm not sure how bad it was."
It is the second time that Tottenham fans have been targeted by an apparent anti-Semitic attack in the last three months. In November, fans of the club, which has a traditionally strong Jewish following, were ambushed inside a pub in Rome on the eve of their game against Lazio. Far-right thugs were blamed for that knife attack, and two witnesses claimed the assaults last night could have had an anti-Semitic motive.
One, who did not want to be named, said: "There were 50 who attacked in the first wave and 25 in the second. It's a pretty scary thing when you're confronted by people doing Nazi salutes. A lit flare was thrown through the window as well as the heavy weight, the kind that's used on terraces to hold down umbrellas. It was terrifying. I've never seen anything like it. They threw iron stools through the windows as well."
Tottenham fan James Taylor drove through the night from his home in Ilford, Essex, to attend the Europa League second round second leg clash. He had no doubt that this was not a random attack. "It was pre-meditated, pre-arranged. It was nothing to do with Spurs fans," he said.
Tottenham Hotspur Football Club said they were aware of reports of the attack.