The world's largest banknote printer said its chief executive has resigned following production problems at one of its facilities.
James Hussey (48), De La Rue's chief executive from January 2009, stood down with immediate effect after telling the board he shouldered responsibility for irregularities at a site thought to be at Overton, Hampshire.
Mr Hussey had been employed with De La Rue for 25 years, including four years as the boss of the security paper and print division at the centre of this summer's crisis.
De La Rue prints banknotes for the Bank of England and 150 other countries.
It said certain paper quality specifications had not been met.
It suspended some production and the shipment of the type of paper involved.
It has not provided further details about the irregularities but said it was confident that neither the physical security nor the security features incorporated in the paper were compromised.
De La Rue said: "The company continues to look into these irregularities in one of its paper production facilities, which the board considers to be of a serious nature."
It added that it may take some time to assess the financial and operational implications on the current year's financial results and prospects.
"All the other activities of the group, including currency printing, remain unaffected by these irregularities."
De La Rue's shares fell to a three year low last month, and were down another 12% yesterday.