• Forty-six Polish fans were arrested after the violence erupted when about 1,000 away supporters were not given tickets, West Midlands Police said.
• The violence outside Villa Park was the worst officers had seen at a football match in more than two decades, the deputy chair of West Midlands Police Federation said.
Aston Villa fans said "all hell broke loose" before the European fixture with Legia Warsaw.
Four police officers and police dogs were hurt in clashes with away fans, with one officer suffering concussion when he was hit by a flare.
Forty-six Polish fans were arrested after the violence erupted when about 1,000 away supporters were not given tickets, West Midlands Police said.
The assistant chief constable said this had sparked the "sustained disorder".
The violence outside Villa Park was the worst officers had seen at a football match in more than two decades, the deputy chair of West Midlands Police Federation said.
Assistant Chief Constable Damian Barratt said he had "no doubt" the failure of Legia Warsaw representatives to distribute the tickets to fans had sparked the "high levels of violence".
Police said they faced 90 minutes of "sustained violence" and all those arrested remain in custody. No home fans were detained in connection with events.
Villa has now lodged a complaint with Uefa against Legia Warsaw after the night's violence, which involved barred fans hurling missiles into the stadium from surrounding streets.
The West Mercia police officer who was concussed was later taken to hospital with smoke inhalation after the smoke from the flare entered his helmet.
The flare set his jacket on fire, but it was removed quickly to minimise his injuries.
Another officer is suspected to have sustained a broken hand.
The force had intelligence beforehand that Legia Warsaw fans were coming over to "cause problems", said Jase Dooley, deputy chair of West Midlands Police Federation.
Officers from Derbyshire, Staffordshire, Warwickshire and West Mercia took part in last night's operation as well as mounted officers from Gloucestershire and Thames Valley.
Villa fan Justin told BBC Radio WM he had been walking to the ground ahead of the game and had just reached the north stand car park when "literally all hell broke loose".
"I turned round and there were flares thrown, things coming over the top. [The police] reacted very, very quickly to shut that down," he said.
Two police horses were punched and kicked, and several police dogs were also injured walking on broken glass after bottles were thrown at officers. They are not thought to be seriously hurt.
"This is unprecedented violence, we've not seen for years and years," Mr Dooley said.
"You've got elderly people, families trying to go to a game and these fans, I would call them hooligans, were intent on causing damage to any person who was walking their way.
"It's just a difficult situation because we knew the intelligence that they were coming over to cause problems and the police gave the operation the fullest attention possible - we've policed it correctly but you just cannot stop the sporadic violence which occurs."
He said the force had given the policing operation for the match "the fullest attention possible".
"We've policed it correctly, but you just cannot stop the sporadic violence which occurs," he added. "Community policing is going to be suffering because of these thugs."
'Ketchup bottles launched'
Forty one people were detained for violent disorder, four for possession of a knife or offensive weapon and four for assaulting emergency workers. All were fans of the Polish side.
Phil Strickley was in Villa's Holte End and said fans outside the stadium had started throwing bottles in, including some picked up from a burger van.
"They were literally picking up all their ketchup bottles and launching them into the stadium, trying to hit our fans," he said.
Villa's Europa Conference League game went ahead and the Legia Warsaw fans were stopped from entering Villa Park over safety fears.
Birmingham councillor Waseem Zaffar was at the game with his eight-year-old son and said some away fans had managed to get into the ground.
"As soon as their team scored, they jumped up and then there was little spats here and there and a few of them got kicked out," he added.
Prof Clifford Stott, from Keele University, who is an expert on the policing of football crowds, was at the game.
"Some of the most serious disorder I've ever witnessed in a Uefa competition context tonight. Legia Warsaw have serious issues to confront and I can't see how Uefa cannot act," he posted on X.
Uefa - European football's governing body - said it strongly condemned the "unacceptable violence" around the game.
"Uefa is in the process of gathering all official reports from the game before deciding on potential next steps," a spokesperson added.
Dutch police officers were injured during large-scale disorder during Legia Warsaw's match against AZ Alkmaar last month.