A malicious email purporting to be from Norfolk County Council led to the authority being temporarily blacklisted by security organisations, it was revealed today.

And that played havoc with the ability of staff at County Hall to send emails, with some arriving hours after they were sent and some being blocked completely.

But the council insisted there was no evidence the authority's security had been breached, despite the 'spoofing' of one of its accounts to send the email.

Council bosses issued a warning to people in the county not to click on a spreadsheet attachment on the emails, which impersonates the address of accountspayable@norfolk.gov.uk

They said the emails originated from outside the council and were designed to trick people into opening malicious content.

A spokeswoman said: 'From Friday afternoon, the council was temporarily blacklisted by a number of security organisations as a direct result of having an email address that was spoofed. This has now been resolved and emails are being delivered as normal.

'The issue has been investigated by Norfolk County Council as a matter of priority and we can confirm there is no evidence that our security has been breached.

'Members of the public who receive an unexpected email from accountspayable@norfolk.gov.uk are advised to delete it and ensure they are running up to date security software.'

The issue followed previous technology problems at Norfolk County Council.

In July, angry councillors were left without access to their emails for more than a week.

In June, Conservative councillor Roger Smith branded a multi-million pound project to transform the council's information technology system as a 'looming catastrophe' Delays and problems had sent it £1.25m over budget.

In April last year, embarrassed council bosses apologised for a computer failure which meant almost 2,000 staff at Norfolk County Council were unable to read or send emails - for more than a week.

At the time, officers admitted they had no way of accessing accounts to find out if vital emails were sat unread.

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