Highlights: Reading 1-1 Cardiff City
Reading say they will review their match-day protocols but are standing behind a decision to report Cardiff City fans for 'discriminatory chanting.'
The incidents happened during the FA Cup draw at Madejski Stadium.
After Saturday's game Thames Valley police arrested four Cardiff fans for "alleged racially aggravated abuse", all later released under investigation
Cardiff, who dispute the allegations, subsequently demanded an apology.
A statement from Reading on Tuesday backed their decision to report "two isolated incidents of discriminatory abuse".
The English club's response continued: "As a result of a statement taken by the police that afternoon, it was deemed there was sufficient evidence to arrest four Cardiff City supporters for alleged racist chanting under the Football Spectators Act. To justify any arrest, there needs to be reasonable grounds.
"These alleged incidents continue to be fully investigated by the Thames Valley Police and we will continue to assist the authorities with these investigations."
On Monday Cardiff asked for an apology, claiming their fans had been labelled as racist.
Cardiff City fans at Reading's Madejski Stadium - the sides meet again in the Championship on 31 January
The Welsh club said: "Language could be heard taking place between fans of both clubs and was of an anti-Welsh/anti-English nature."
Their statement added: "We also question (Reading's) protocol and procedure on the day and welcome a full investigation into its use for the benefit of both our clubs and indeed British football."
Reading have now said they will review their decision to make a public announcement during the game and offered an apology to the majority of Cardiff fans who attended the match.
"We would like to apologise to all supporters of Cardiff City Football Club who played no part in any discriminatory abuse and feel that their character has been blemished unwarrantedly by the announcement which was made over the PA system at Madejski Stadium.
"Reading Football Club are liaising with the relevant football authorities to consider how football-wide protocol issued to us was implemented in this instance and we will review our procedure regarding public matchday announcements of this nature accordingly."
Their statement concluded: "Discrimination of any form is not ok and all supporters who visit Madejski Stadium are reminded that instances of discriminatory behaviour will not be tolerated."
The Football Association is investigating and has asked both clubs for their observations.
The two clubs meet again on Friday night in the Championship at Cardiff City Stadium, with the Royals returning to the Welsh capital for the FA Cup fourth-round replay on Tuesday, 4 February.
Source: bbc.com