WestLB, the German bank, could be facing a criminal inquiry now its regulator has given the country's state prosecutor documents relating to losses on a deal done by Robin Saunders' principal finance unit.

The bank said in a statement: "In connection with the regulatory investigation into risk provisioning at WestLB, the German Financial Supervisory Authority (BaFin) has passed on documentation to the public prosecutor´s office in Düsseldorf. The public prosecutor´s office will now have to decide whether there is a preliminary suspicion of possible criminal relevance.