The glitch has left many consumers unable to use their cards in cash machines and eftpos terminals around the country and also hit German cadholders travelling overseas.

Smart card supplier Gemalto issued a statement late Tuesday saying that it is actively working with German banks to develop "a corrective process that avoids the replacement of the affected cards in Germany".

Other large suppliers to the German banks, Giesecke & Devriant, Oberthur and Sagem Orga, say that their cards continue to function normally.

In a statement, the DSGV savings and regional banking association says that around 20 million "electronic cash" (EC) cards, and 3.5 million classic credit cards issued by its members have been affected by the bug, which it describes as a delayed "Year 2000 problem".

A further 6.5 million cards issued by private and co-operative banks have also been hit.

DSGV says it expects to resolve all the problem by early next week, but warns that consumers may experience "withdrawal restrictions" on some credit cards until then.

ZKA (Zentraler Kreditausschuss - the German Central Credit Committee) says acceptance of cards in cash machines and eftpos terminals is gathering pace in Germany, but that travellers may continue to experience problems.

Olivier Piou, Gemalto CEO, comments: "We are fully focused on minimising the inconvenience for the cardholders. As a partner, we will of course meet our contractual obligations, and continue to support our clients. We trust that we will promptly deploy a solution with our German customers to return to full normal operation."

He adds that Gemalto cards issued in other countries have not been affected.

Similar Y2K time bombs have exploded in Australia, where merchant terminals supplied by KeyCorp skipped six years ahead and refused to recognise cards issued by Bank of Queensland. The affliction, which also spread to some BankWest customers, was fixed following an overnight software patch that was downloaded to affected terminals on Tuesday.