Brighton have apologised to Crystal Palace after excrement was found in their dressing room before last week's Championship play-off semi-final at the Amex Stadium.
The Seagulls confirmed weekend reports about the incident and have since launched an investigation into events before Palace's 2-0 aggregate victory.
In an email sent to season-ticket holders, Brighton chief executive Paul Barber revealed the club had formally apologised to their rivals and vowed to tighten security at the ground.
But Barber was unable to comment on the suspension of manager Gus Poyet, assistant Mauricio Taricco and first-team coach Charlie Oatway - for matters unrelated to the incident.
"It's clearly been a challenging week for our club," wrote Barber.
"Defeat at home to our biggest rivals in a play-off semi-final; the suspension from work and pending investigation of three members of our staff; and the revelation of an unsavoury incident that took place in our visitors' dressing room last Monday.
"These events have led to some unwelcome headlines that we all would have preferred not to have been reading during the last week.
"We apologised to Crystal Palace as soon as the vandalism in their dressing room was discovered, and again more formally a few days after the match. As a result of what happened, please rest assured we have reviewed our internal procedures to guard against this ever happening again.
"On other matters, you will appreciate that I'm unable to comment further at this time."