The European Central Bank (ECB) has ordered the printing of an extra 640 million euro bank notes after admitting it had under-estimated the number that will be needed for the cash launch on New Year's Day.

The ECB's move follows mounting concern that shoppers could face chaos in January because retailers won't have enough euros to give in change.

The new euro notes and coins will be used by 300 million citizens in 12 countries - the biggest currency switch over ever attempted.

Retailers have been arguing for months that the public won't have enough cash on 1 January when euro notes and coins are launched.

Stores demand

The big stores, supported by the European Parliament, have demanded that the public be issued with euro bank notes before launch day.

But the ECB has steadfastly refused to do this because of what it says would be the increased risk of counterfeiting.

Now the bank has been forced to admit it miscalculated the quantity of euro bank notes that will be needed.

The ECB is ordering mostly low denomination bank notes, particularly five and ten euro bills.

The bank says the move will reduce the problem of shoppers only being able to draw out high value notes from bank cash dispensers.

Small is beautiful

Putting more small notes into circulation should ease the pressure on retailers, the bank argues.

Stores have been worried that if most customers paid with large bills they'd have to hold even bigger quantities of euro change - a massive logistical and security headache.

The ECB's announcement means almost 15 billion euro bank notes will now be brought into circulation, but it insists the extra production should not cause problems for the bank note printers.