A “Year 2010” software problem triggered by the change of decade has affected 30 million German debit and credit cards and left bank customers unable to make purchases or make cash withdrawals.



But German banks appear to have been unprepared this month for the emergence of the fault, which has been attributed to a software glitch in the microchips embedded into many “chip and pin” cards and has meant they have not coped with the change to 2010.



In what has given the notoriously thrifty consumers of Europe’s largest economy another reason to curb their spending, Germany’s savings bank association admitted on Tuesday that a “belated year 2000 problem” had affected more than 20m of 45m debit cards issued by the public-sector.



A further 3.5m of 8m credit cards were also affected, according to the association, which represents the small institutions that hold the greatest share of the country’s retail savings.



The association of private sector banks said 2.5m of 22m cards were affected, while the association of mutual banks said the problem was restricted to 4m of the 27m debit cards issued by its members.



Customers have reported being unable to use the cards to withdraw cash from ATMs or make payments in shops. Many have also been unable to use their cards in shops or cash machines outside Germany.