Leicester City said they are appalled after one of the club's supporters ran on to the pitch and attacked Nottingham Forest players during their heavy FA Cup defeat on Sunday.
The Cup holders went down 4-1 to their Midlands rivals and later issued a statement to condemn the fan who charged on after Forest's third goal and aimed punches before being bundled away.
"The club is appalled by such behaviour and offers its apologies to Nottingham Forest and its players whose safety was compromised," Leicester said in a statement.
"We applaud the swift action taken by City Ground stewards in apprehending the individual involved, who will be subject to a lifetime ban from all Leicester City fixtures at home and away. We will offer every support to the relevant authorities in pursuing further appropriate action."
It was the first meeting between the rivals for eight years.
