A 16-week jail term handed out to a Leeds United fan on Monday for attacking former England goalkeeper Chris Kirkland in a match against Sheffield Wednesday was too lenient, the Championship (second tier) club said.Aaron Cawley, 21, from Cheltenham, pleaded guilty at Sheffield Magistrates' Court to assault and invading the pitch during the game at Hillsborough on Friday.Wednesday keeper Kirkland was pushed in the face by Cawley and shoved to the ground moments after conceding an equaliser in the 76th minute. After treatment he was able to continue for the remainder of the game which ended 1-1."While we are pleased to see justice brought so quickly, our one disappointment is that we feel the sentence could, and should, have been considerably longer," Leeds said in a statement on their website (www.leedsunited.com)Cawley was given a five-year football banning order by the court and Leeds said he would be banned for life from attending games at Elland Road.