More than a thousand Blues supporters invaded the pitch and confronted 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 and seats were also ripped out and used as missiles along with other objects.
The Football Association immediately pledged to carry out a full investigation and a spokesperson said: "We wholly condemn the actions of any individuals who have been involved in the scenes of disorder at St Andrew's.
"The FA abhors acts of violent behaviour and we urge the clubs and authorities to identify any individuals involved in disorder, and impose the stiffest available sanctions, including banning orders.
"The FA will fully investigate the matter in conjunction with the appropriate authorities.
"The whole of English football has worked hard to eradicate scenes of disorder from our game.
"Home Office figures this week showing a significant drop in arrests at the many thousands of football matches held every week, the majority of which still pass trouble free."
Birmingham have also promised a full investigation in co-operation with the FA and police into the ugly scenes.
A club statement read: "Birmingham City Football Club is disappointed with scenes at St Andrew's following the Carling Cup tie against Aston Villa.
The club does not tolerate the breaking of any stadium rules and will conduct a full investigation in conjunction with the FA and police and take appropriate action."
Source: PA
Source: PA