South Tyneside Council has refused to reveal whose computer was used to post the allegations against sisters Geraldine White and Karen Nicholson under the pen name 'Brenda' on local blog Curly's Corner Shop, late last year, which remained on the site for nearly a week.

Today Mrs Nicholson vowed to take the council through the civil courts and have the identity revealed in their fight to claim damages for defamation.

'Brenda' accused the sisters of rigging a Labour party selection ballot eight years ago, in the now-defunct Rekendyke ward. An investigation by Labour chiefs at the time discovered that neither sisters had touched the ballots, and they remain in a solicitor's safe eight years on.

Graham Rigg, the man behind the blog, revealed the IP address of the writer, which was tracked down to a computer operated by South Tyneside Council.

An internal investigation by council bosses pinpointed the computer and the time of when the message was posted to within a few seconds.

Chief executive Irene Lucas then had to weigh-up the sisters' right to know, in contrast with the restraints of the Data Protection Act and Human Rights Act.

However, in a letter to the sisters, Ms Lucas wrote: "After careful consideration of the points that you made in your letter and the points made by the person I spoke to, I have decided I do not think that it would be right for me to disclose it to you."

She also explained that she's approached the individual concerned, adding: "That person has categorically denied to me that they were responsible for posting the items on to the blog."

The sisters will now take their fight to the civil courts to discover who posted the message.

Mrs Nicholson, from Biddick Hall, South Shields, said: "It's a disgrace, it's an absolute scandal. We won't let this lie and we'll be taking this to court.

"Why should someone be able to use a council computer to defame a member of the public without consequence?"

Mrs White, former chairman of the South Shields Labour Party, from Lincoln Road, South Shields, added: "This decision seems to show that those in the Town Hall can write anything they like about private citizens living in the borough."

However, a spokesman for South Tyneside Council said: "South Tyneside Council has taken this matter very seriously and acted immediately when the complaint was put to us.

"The investigation is now complete and the council has identified a potential computer that may have been used to send the blog entry.

"South Tyneside Council now has to balance the interests of all parties in an area where Data Protection and Human Rights law apply as well as the rights of Mrs White and Mrs Nicholson regarding the publishing of information on a blog site.

"Mrs White and Mrs Nicholson have been recommended to apply for a court order which would ensure a fair balance is struck and offer legal protection to South Tyneside Council for any disclosure".

Rumours are rife on local Internet sites about the identity of the person who posted the comments.

Mr Rigg wrote on one local site: "This intrigue is all rather entertaining."

Blogger Peter Shaw added: "A plethora of unanswered questions now lie on the table. The sooner they are answered, the sooner all these matters can be drawn to a conclusion.

"Somebody, somewhere, will be named and shamed."