The club have commented on complaints from Town fans regarding the significant number of Colchester supporters in home sections during Saturday's game. Several fans wrote to the Blues complaining about abusive and aggressive behaviour from infiltrating opposition supporters.
A Town spokesperson said: "We are aware that a significant number of Colchester United supporters were able to obtain tickets to many areas of Portman Road on Saturday. This was despite checks being conducted by ticket office staff.
"Some of these individuals were able to gain entrance through legitimate Ipswich Town supporters buying tickets on their behalf.
"Due to the close proximity of both teams and the fact that Ipswich Town Football Club enjoys extensive support from fans in the CO postcode area, it was extremely difficult to identify all Colchester fans, although several hundred were picked up during the checking process.
"Although committed to providing 2,000 tickets for the visiting supporters, ITFC allocated 2,280 to U's fans.
"Stewards were briefed ahead of the match to eject any Colchester fan in the North Stand and to monitor and take appropriate action with those in the three remaining areas of the ground. This policy led to some visitors being ejected, moved to the visitors section or being closely watched.
"Whenever alerted to potential difficulties we would expect our stewards to take whatever appropriate action to ensure the safety of our supporters. We will investigate any direct communication received and act upon our findings.
"It should be remembered that, although a small number of visiting fans in the home supporter areas did not control their behaviour, many decent Ipswich and Colchester supporters sat alongside each other in harmony enjoying a competitive and entertaining match without causing offence or distress to their fellow supporters."