Leeds United fans who have illegally bought tickets in areas reserved for Bradford City supporters at Sunday's match can expect to be thrown out of the ground or even arrested as the clubs operate a 'Zero Tolerance policy'.
The chairmen of both clubs called a joint press conference to issue the warning.
An unknown number of Leeds fans are suspected of buying tickets for blocks E, F and G of the Ciba stand at Valley Parade, reserved for home supporters.
Fans in the vulnerable areas will be handed leaflets before Sunday's 4pm kick-off, advising them of the clubs' intentions.
Anyone seen celebrating a Leeds goal or causing trouble would be ejected from the ground or arrested, said City boss Geoffrey Richmond.
The game will be the most heavily policed in Bradford City's history and extra stewards - 250 in all - are being drafted in.
"We have decided to be proactive and there will be a Zero Tolerance policy within the stadium on Sunday," said Mr Richmond.
Fears over segregation have arisen due to a club policy to keep 1,400 tickets in the Ciba stand back for sale on a match-by-match basis. It was very difficult - if not impossible - for the ticket office staff to be sure if they were selling them to genuine City fans or Leeds fans, said Mr Richmond.
"There may be away supporters in some home areas, and looking at the Internet, there's a feeling that certain elements of either side are looking for trouble," he said.
He appealed for Leeds fans with Ciba Stand tickets to return them to the ticket office. "We will ask no questions and provide a full refund."
Peter Ridsdale, the Leeds United chairman, said any Leeds United fans found to be causing trouble faced a lifelong ban from Elland Road.
Meanwhile, a fourth Leeds United player has been arrested and questioned in connection with an assault on an Asian student, it emerged today. Defender Michael Duberry, 24, was questioned for several hours and released on police bail. He is not suspected of taking part in the violence.
Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article