US banking giant Citigroup could face disciplinary action by the Eurex exchange, regional state authorities in Frankfurt said on Monday. Eurex's disciplinary committee would examine the controversial bond trades by Citigroup, after an inquiry by the regional stock exchange authorities in the German state of Hesse found evidence of breach of trust, Hesse Economics Minister Alois Rhiel, said in a statement. Rhiel, who is in charge of regulating Frankfurt's financial markets, said the committee could fine the bank or its traders up to €250,000 ($330,000) or impose a 30-day trading ban. The body normally rules within eight weeks, but it could take longer due to the case's complexity, he added. In August, Citigroup flooded the cash market with €11 billion euros in sell orders on euro-zone government bonds, causing rivals to rush to hedge their exposure in the Eurex market for German government bonds by selling the futures. About half an hour later, Citigroup allegedly bought back €4 billion of the bonds at a lower price, raising suspicions of market manipulation. Citigroup allegedly made a profit of around €17 million on the deal. Citigroup also carried out related trades on the Eurex derivatives exchange. The German financial market regulator BaFin has already asked prosecutors to probe the case and Italian regulators are also looking into the trades.