Hamburg - Fans of Dutch side Ajax Amsterdam have clashed with police in the northern German city of Hamburg ahead of a UEFA Cup tie in the city later Thursday.

Just hours before the game against Bundesliga side SV Hamburg, around 450 Ajax fans blocked the Reeperbahn, the famous red district in the city, breaking windows of a hotel and holding up traffic for around 40 minutes, said police spokesman Ralf Meyer.

On Wednesday night, between 30 and 40 Ajax supporters smashed up a local bar before attacking police called to the scene. Around 40 people were taken into custody as a result.

"Around 50 or 60 glasses were broken and the furniture was destroyed," said Meyer.

A shot was also fired when three plain-clothes officers were surrounded by a mob of around 50 fans. The alleged ringleaders were later picked up in another bar, including a well-known hooligan from Amsterdam, who has a life ban from Ajax games in the city.

Police have more than doubled the number of officers normally on duty for a Hamburg match to 800 for Thursday's game. In comparison, there were 300 police on duty last Sunday for the match against neighbours Werder Bremen.

"In the Bundesliga we generally don't have to worry about problem fans," said Meyer. dpa