Carling Cup winners Birmingham have been charged by the Football Association with failing to keep supporters off the pitch following their quarter-final victory over Aston Villa.
More than 1,000 Birmingham supporters invaded the pitch after their side's 2-1 win at St Andrew's and confronted the 3,800 Villa fans situated in the Gil Merrick Stand at the other end of the stadium.
A flare appeared to be thrown into the section housing the Villa supporters although it was then tossed backwards and forwards between the rival factions.
Seats were also ripped out and used as missiles along with other objects.
The FA today described the incidents as "serious crowd disturbances" and have given Birmingham until next Friday, March 11, to respond.
Birmingham said in a statement they "would like to thank the FA for their assistance and communication prior to and during the investigation".
On the night of the disturbance, Birmingham manager Alex McLeish called it a return to the "dark ages" - a reference to the trouble which blighted the game in Britain in the 1970s and early 1980s.
The police presence in and around St Andrew's had been swelled to nearly 500 officers for the first midweek meeting between the clubs since ugly scenes seven years previously.
Blues acting chairman Peter Pannu added at the time: "Whilst we are very happy with the victory, we are extremely disappointed with the events that took place after the game.
"I promise there will be an impartial investigation by the club as we do not condone the embarrassing actions of certain individuals."