Commerzbank said Wednesday it has suspended two currencies traders, alleging it caught them in the act of attempting to manipulate foreign-exchange rates. The two traders were trying to move the Polish zloty's rate against the euro, according to a person familiar with the matter

All told, around a dozen banks around the world have suspended or fired at least 30 traders and sales people in a year-long investigation into currencies trading practices. The comments from the German lender after its first suspensions over the matter form the most detailed explanation for disciplinary action to date, and offer further evidence that the global probe is spilling beyond the most heavily-traded currencies and into emerging markets.