A mother has been given permission to change the surname of her three-year-old twin sons because of the 'bizarre conduct' of their father.

The woman, who cannot be named, told a family court judge that her children they needed protecting from their father's internet blogging 'activities'.

Judge Ross Duggan said the man, who had not seen the children for a year after separating from his wife, is embroiled in litigation about what contact he should have with them.

Ruling: A mother will be allowed to change the surname of her twins because of the 'bizarre conduct' of their father on his blog (posed by model)

He said the man had a 'perception of martyrdom' and had created a 'protest blog' which he updated 'virtually daily'.

Judge Duggan said the man had 'taken to referring' to his estranged wife as 'a drug-addicted alcoholic who suffered from sexually transmitted diseases'.

He also said he had posted a medical report relating to one his children, had posted 'extensive details' of litigation issues and had posted his sons' names.

The judge said the man had 'let himself down' - and said his 'activity' had been 'severely damaging' to the welfare of the children.

And he concluded that allowing the woman to change the children's names was 'necessary and proportionate'.

Ruling: The Royal Courts of Justice in London, which has a family division where statements on rulings of family matters are often read out

Detail of the case has emerged in a ruling by Judge Duggan following a hearing in Preston, Lancashire.

I cannot allow a situation in which the children at an older age and their friends can chance upon web-based insults to the mother ... or anything else that the father decides to publish from time to time in association with their name Judge Ross Duggan

The judge said the family could not be identified.

'I am persuaded that the desirable preservation of a symbol of a paternal link through the preservation of the surname has to give way to the protection of the children from the father's publication steps,' said Judge Duggan.

'I cannot allow a situation in which the children at an older age and their friends can chance upon web-based insults to the mother ... or anything else that the father decides to publish from time to time in association with their name.

'It seems I cannot realistically stop the father's activities at source but I can stop the harmful consequences, which are, of course, associated with the identification of this material alongside the names of the children.