Ajax have been fined €25,000 (£21,000) by UEFA after fans displayed an offensive banner at their Champions League home game against Celtic.
The Dutch club announced the sanction on their website and also confirmed another case is ongoing concerning crowd trouble at the return fixture in Glasgow.
The club's statement read: "Ajax have been fined by UEFA after a banner appeared on the stands of the Amsterdam ArenA during the match against Celtic FC. The banner was aimed at Ajax's opponents that night. UEFA imposed a fine of 25,000 euros.
"The possible penalty for such an offense is a fine of 50,000 euros plus the closure of some parts of the stadium at the next European home game. After a prompt and adequate response from Ajax the fine was halved and the partial closure averted. The penalty will be recovered from those responsible.
"Another case is in process arising from disturbances during Ajax's match against Celtic FC in Glasgow. A ruling is expected to follow on Thursday, November 21."
The banner carried a sectarian message and appeared in the same area of the ground as flags pertaining to the 'F-Side' hooligan group of Ajax fans.