Shares of security printer De La Rue have fallen to a two-year low following the company's admission that it has recently discovered quality and production irregularities at one of its mills—believed to be Overton in Hampshire—which produces the paper used in banknotes. DLR prints notes and supplies security paper for approximately 150 central banks worldwide. Production and shipment of the paper has been suspended while DLR carries out an investigation and attempts to determine if the substandard paper has ended up in circulation.