Some De La Rue staff "deliberately falisfied" tests that forced it to halt banknote shipments and warn on profits, the world's biggest banknote printer said.

Shares in the company, which makes paper for more than 150 currencies around the world, fell a further 5pc on Tuesday after the announcement.

They have now fallen more than 28pc since June when De La Rue suspended part of its operations at its largest plant after "quality and production irregularities" without giving details.

"Banknote paper specifications have a large number of detailed parameters and the investigation has found in certain cases that a small number of them have fallen marginally short of specification."

It gave no indication of how many staff were involved.

The investigation into production irregularities at its printing plant in Overton, Hampshire are continuing, the board said.

De La Rue said all paper production is now within specification and it is ready to resume supply of fully compliant paper as soon as customers agree.

It did not name the customers.

The company remained confident that neither the "physical security nor the security features in the paper have been compromised".

To read the complete article, see:De La Rue staff 'deliberately falsified' banknote tests(www.telegraph.co.uk/finance/newsbysector/epic/
dlar/7986964/De-La-Rue-staff-deliberately-falsified-banknote-tests.html)

To read a related article in The Guardian, see:De La Rue faces Serious Fraud Office inquiry over 'falsified documents'(www.guardian.co.uk/business/2010/sep/07/de-la-rue-serious-fraud-office)