German investigators said Thursday they had obtained a letter written in Italian in which a group calling itself the Informal Anarchist Federation claimed responsibility for a letter bomb sent to Josef Ackermann, head of Deutsche Bank.

The letter speaks of three explosions against banks, bankers, fleas and bloodsuckers, the Criminal Investigations Office for the state of Hesse and Frankfurt prosecutors said in a statement, adding that this meant two more letter bombs may have been sent.

(Reporting by Alexandra Hudson)