The issue of the next series of Swiss bank notes has been delayed by “unexpected technical problems”, the Swiss National Bank (SNB) announced on Thursday.

It did not elaborate, but said the delay would be of “at least one year”.

However, a bank spokesman told the AP news agency that “anti-forgery features in the notes have never before been used in large-scale print runs”.

“The SNB will announce the issue date as soon as the first banknote denomination is ready for distribution,” the bank said in a statement.

Issue of the new notes had already been postponed in 2010 because of the time needed to develop innovative security improvements. It was then announced that the first note of the new series should come into circulation at the end of this year.

The bank says the current series continues to offer a high standard of security and the supply is guaranteed at all times.

The new series depicts Switzerland “as a meeting place and platform for organisation, creativity, adventure, humanity, progress and dialogue”.

The current series of banknotes, the eighth, features famous Swiss and went into circulation between 1995 and 1998.

The sixth series stopped being legal tender in 2000. The seventh series was never issued: it is being kept as the reserve.

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