West Ham and Fiorentina have been charged by UEFA for incidents surrounding the Europa Conference League final in Prague earlier this week.
The Hammers have been charged with invasion of the field of play and throwing of objects, while the Serie A side are charged with throwing of objects and lighting of fireworks.
Disciplinary proceedings have been instigated in accordance with Article 55 of the UEFA Disciplinary Regulations.
The game was halted after a cup thrown left Fiorentina captain Cristiano Biragi bleeding from the head.
Plastic pint glasses were hurled from the West Ham end throughout the first half at the Eden Arena in Prague.
Referee Carlos del Cerro Grande eventually halted play after Fiorentina captain Biraghi was hit by another object as he went to take a corner just after the half-hour mark.
Biraghi suffered a cut to the back of his head and required treatment and a bandage.
A message over the PA system urged supporters to stop throwing things on to the pitch and to respect the players, before play eventually resumed with the score still 0-0, before West Ham went on to win 2-1 thanks to Jarrod Bowen’s last-minute goal.
West Ham released a statement condemning fans who threw objects onto the pitch during Wednesday’s Europa Conference League final in Prague.
“West Ham United unreservedly condemn the behaviour of a small number of individuals who threw objects onto the pitch during tonight’s UEFA Europa Conference League final,” the statement read.
“These actions have no place in football, and do not in any way represent the values of our football club and the overwhelming majority of our supporters, who have behaved impeccably in Prague this week and throughout our last two seasons in European competition.
“We will work with the police and other stakeholders to review the incidents and act against anyone found guilty of an offence. In line with our zero-tolerance approach, anyone identified will have their details passed to the police and will be given an indefinite ban and therefore be unable to enter London Stadium and travel with the club.
“There is no place for this kind of behaviour at West Ham United.”
Earlier on Wednesday, police in Prague arrested more than 30 people after violence broke out ahead of the game in the city centre.
It is thought a group of West Ham fans were drinking in a bar in the centre of the city when they were attacked by large numbers of men dressed all in black. As other West Ham supporters arrived on the scene, riot police moved in to keep the rival groups apart.
Czech police confirmed three people were injured and one policeman was also attacked.
They said in a statement: “Italy fans attacked West Ham fans in a bar in Rytirska Street, injuring three. One policeman was also attacked.
“We have restricted the personal freedom of 16 people and we are currently investigating the whole incident.”
Around 20,000 West Ham fans were in Prague, the majority without tickets, for the final between the Hammers and Fiorentina, which kicked off at Slavia Prague’s Eden Arena at 9pm local time.
Violence marred the end of West Ham’s semi-final second-leg victory over AZ Alkmaar in the Netherlands, when home supporters attempted to get at a group of the players’ family and friends in one of the main stands.
An eyewitness told Sky News: “There were five or 10 Italian guys running across the street, they had some weapons. They were attacking each other, there were a lot of fireworks going off and so much glass.
“Two or three English people were hurt, but that’s it.”
Outside the Tek’ila Tek’ila bar in the city centre, a burnt-out chair and broken glass were seen littered across the ground.
One West Ham fan, who did not want to be named, said “a large group” of Italian fans attacked the bar.
“About eight Italians walked past, swinging bands and chains,” he said.
“Five minutes later there was a big group that come down the road and attacked us.”
The man said five West Ham fans were injured.
He said: “Three of our mates [were injured], out of all of this lot there were five. Three of them were our mates. They’ve gone to hospital.”
He added one of his friends was “quite badly” injured with a “massive cut” on his head.