Hamburg - The German football federation DFB is investigating the behaviour of St Pauli Hamburg player Deniz Naki during a trouble-marred second division match at Hansa Rostock.

The DFB said on Tuesday that Naki was accused via television evidence of making a cut-throat gesture towards Rostock fans after scoring for St Pauli in a 2-0 victory on Monday night.

He faces sanctions for unsportsmanlike conduct. The DFB is able to take action because the incident went unnoticed by the referee.

Earlier the match was stopped for three minutes after St Pauli's first goal when fans in the visitors' section of the stadium set off flares.

A DFB investigation into this incident was also expected.

After the game, police used water cannon and arrested 23 fans in violent clashes with Rostock fans. Seeveral officers were slightly injured, police said.

Matches between St Pauli and Rostock have been overshadowed by violence for the past years. Some 500 officers were on hand for Monday's game.

The Rostock trouble was the latest in Germany after several incidents around lower-league matches over the past days.

A police officer was seriously injured after being attacked by KFC Uerdingen fans in the western German town of Krefeld on Sunday, while 36 people were injured and 50 arrested during riots around an eastern German game between FSV Zwickau and Erzgebirge Aue.

Last week, police in the Saxony-Anhalt state said they would be seeking attempted murder charges against hooligans after an incident in late September when masked fans launched an attack on police at a regional game between Hallescher FC and Magdeburg. (dpa)