A problem which prevented staff at Norfolk County Council from getting into emails today is believed to be a network issue, rather than a cyber attack, County Hall bosses have said.

A county council spokesman apologised for the problem, which meant staff had been unable to access emails since about 10am this morning.

As of 10.15pm Thursday night, the council confirmed it was back online and would be investigating the reasons behind the black-out.

The spokesman said: 'The network fault we experienced earlier today appears to have been resolved following extensive work by our ICT staff.

'We will be in talks tomorrow with BT to understand more about why the fault occurred. We would like to repeat our apology of earlier today for any inconvenience caused.'

Earlier in the day, he said: 'Norfolk schools were unaffected by the fault and our social services system continued to function, as do our telephones, although we have asked people to only call if absolutely necessary.

'We are confident this is a network fault and not the fault of a cyber attack.'

In November, a malicious email purporting to be from Norfolk County Council led to the authority being temporarily blacklisted by security organisations,

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.

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.