Sussex police have been forced into an embarrassing climbdown after admitting their claim that significant numbers of Crystal Palace fans had attempted entry to the derby at Brighton & Hove Albion armed with “knives and knuckledusters” was false.

The police apologised to both clubs and their supporters after chief inspector Simon Nelson, who led last week’s policing operation at the clubs’ first meeting for more than four years, had suggested a day after the goalless draw that incidents around the fixture had represented “a return to the dark days of football”. He had gone on to state, apparently much to Brighton’s frustration: “A significant number of people attempted to enter the ground with pyrotechnics, knives and knuckledusters, which were found following efforts to gain access through fire exit doors in the south stand.”

With preparations for the clubs’ FA Cup third-round meeting back at the Amex Stadium next month under way, Nelson revisited the issue on Thursday morning, taking to Twitter to claim Albion staff had “found those items in the away end of the stadium”. A number of smoke bombs and flares are understood to have been discovered after police escorted around 200 away fans, the vast majority with valid tickets, back to Falmer station with the game under way, but the allegation that knives and knuckledusters had been found was always strongly disputed by Palace’s support.

Neither club made mention of weapons being found in their own statements, issued in the aftermath of the game. Sussex police fielded a number of media inquiries and one freedom of information request on Thursday, submitted by Robert Sutherland of the Palace fanzine Five Year Plan in the wake of Nelson’s tweet, before admitting no weapons had been retrieved. “The reference to weapons being found discarded at the stadium following the Brighton v Crystal Palace match on November 28 was based on information logged by our officers on the night and done so in good faith,” read a statement.

“Subsequently, it has been established that no such items were physically recovered at the stadium or in the city. We accept that this information was incorrect and the tweet published earlier today by one of our officers was wrong. Sussex Police apologises to both clubs and their supporters.”

Sussex police subsequently amended their original statement, still insisting a large number of Palace fans had attempted to gain access without tickets but removing all mention of the weapons. However they did not amend the time or date on the statement and made no reference to the fact that it had been changed.

Sutherland, who was waiting to be contacted directly by Sussex police, said: “Crystal Palace fans are a passionate group. We are proud of our positive support. The implication that our fans would carry potentially deadly weapons into a football stadium was a smear that needed to be challenged. Football fans already have a bad reputation, often unfounded – it shouldn’t be further trashed by unsubstantiated assertions like this one.

“I am delighted Sussex police have apologised for their false statements. Further questions should be asked about the checks that the police force went through to establish the facts prior to making this statement. Clearly in this case, any process they should have followed failed.”

Next month’s Cup tie will take place on a Monday night, partly due to engineering works on train lines between London and Brighton over third-round weekend, with Palace expected to be granted a similar allocation of around 2,000 tickets. Brighton are satisfied with their stewarding of the original game within the stadium.

Yet talks will take place between Sussex police and both clubs in the hope of avoiding a repeat of the incidents which did occur last week – smoke bombs and flares were let off in the away end, with some fans having apparently gained access through a fire exit – with all parties scrutinising CCTV footage to identify any offenders. Six arrests were made on the night, with two stewards, one from each club, hurt in clashes outside the ground.

Nelson tweeted: “I personally add to this apology – the information regarding discarded weapons and pyros in the away end of the stadium was passed to us and believed to be true – this was clearly not the case.”