Officers detained the fans on suspicion of conspiracy to commit violent disorder in raids on Tuesday and Wednesday.
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Trouble flared at last Tuesday's first leg of the Carling Cupsemi-final between Manchester City and Manchester United at Eastlands.City won the game 2-1.
Police hope the arrests will deter fans from misbehaving attonight's return leg at Old Trafford. Seven men, aged between 18 and52, were arrested during raids across Greater Manchester, Preston,Lancashire and Bradford, West Yorkshire, today. Four other men, agedbetween 17 and 30, were arrested on Tuesday, Greater Manchester Policesaid.
One of the four handed himself in after spotting himself on a CCTV picture circulated by police.
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Detective Chief Inspector Mark Roters, of Grey Mare Lane CID, said:'Many families, including women and young children, attend footballmatches so it is totally incomprehensible that a small number ofmindless thugs would incite violence when they are surrounded by peopleclearly terrified by their actions.
'Football related disorder is a stain on the game and we have beenworking hard with both clubs and members of the public to identifythose involved.
Manchester police release CCTV pictures of derby disorder suspects at United against City'These arrests act as a strong warning ahead of the reverse leg thisevening to anyone prepared to get involved in this type of behaviourthat we will come after you.'
Eighteen arrests were made last week after the match and appealshave been made by the police and the Football Association for calmahead of tonight's game.
Anyone with information should call Crimestoppers on 0800 555 111
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